---
product_id: 996167
title: "Motorola SURFboard SB6121 Cable Modem (SB6121)"
brand: "arris"
price: "€ 224.27"
currency: EUR
in_stock: true
reviews_count: 8
category: "Arris"
url: https://www.desertcart.com.cy/products/996167-motorola-surfboard-sb6121-cable-modem-sb6121
store_origin: CY
region: Cyprus
---

# Up to 172 Mbps download speed 4 bonded downstream & upstream channels Gigabit Ethernet port for ultra-fast wired connection Motorola SURFboard SB6121 Cable Modem (SB6121)

**Brand:** arris
**Price:** € 224.27
**Availability:** ✅ In Stock

## Summary

> 🚀 Own your speed, skip the lease, surf the future!

## Quick Answers

- **What is this?** Motorola SURFboard SB6121 Cable Modem (SB6121) by arris
- **How much does it cost?** € 224.27 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.cy](https://www.desertcart.com.cy/products/996167-motorola-surfboard-sb6121-cable-modem-sb6121)

## Best For

- arris enthusiasts

## Why This Product

- Trusted arris brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Blazing Fast Speeds:** Experience lightning-fast internet with up to 172 Mbps download and 132 Mbps upload speeds, perfect for streaming, gaming, and remote work.
- • **Plug & Play Simplicity:** Super-easy setup with major cable providers like Cox, Spectrum, and Xfinity—ditch the rental fees and own your connection.
- • **Future-Proof IPv6 Ready:** Stay ahead with built-in IPv6 support, ensuring compatibility with next-gen internet protocols and faster data handling.
- • **Robust Wired Connectivity:** Equipped with a gigabit Ethernet port for reliable, high-speed wired connections to your computer or router—no WiFi included.
- • **Seamless Multi-Channel Bonding:** 4 downstream and 4 upstream bonded channels ensure stable, low-latency connections even during peak hours.

## Overview

The Motorola SURFboard SB6121 is a DOCSIS 3.0 cable modem delivering up to 172 Mbps download and 132 Mbps upload speeds via 4 downstream and 4 upstream bonded channels. Compatible with major cable providers (excluding Verizon FiOS and AT&T U-verse), it features a gigabit Ethernet port for wired connections and supports IPv6 for future-proof internet. Ideal for professionals seeking reliable, high-speed internet without monthly rental fees, it offers easy setup and a 1-year warranty.

## Description

Product Description A new and improved version of the world's most widely deployed DOCSIS cable modems. For the residential cable subscriber who wants a powerful modem capable of delivering a high-speed data service at blazing fast speeds.10 / 100 / 1000 Base-T Ethernet Port (RJ-45) and 1-Year Limited Warranty. Additional information:• Requires CABLE Internet Service, if not sure your provider is CABLE call them to confirm • Compatible with ALL Major CABLE providers like Comcast, Cox, Charter, Time Warner, Mediacom, Bright House desertcart.com

Review: Smaller, Faster, and Better, too !! - I was one of the first to get a Motorola SB6120 -- and was very much satisfied with the ease of set-up, the awesome speeds, the functionality, and the workmanship. But, like all electronic gizmos, they tend to crap out after a few years. When my SB6120 started dropping upstream channels, I looked to Motorola once again -- right here at desertcart -- and found the new Motorola SB6121. After checking the specs, I found that the new SB6121 Model has the latest IPV6 technology (higher bandwidth capabilities)that were not available on the SB6120. The newer IPv6 technology allows connection speeds up to 160 Mbps., against the 150 Mbps of the SB6120. IPV6 is not in common usage yet, but it will be pretty soon -- And the SB6121 will be ready with the fastest speeds available!! The new SB6121 is a super-easy set-up, and the connection speeds are fast and steady. Comparing the DOCSIS 3 SB6120 to the newer SB6121 : 1.- The Sb6121 is smaller (height and depth are smaller, width is greater). 2.- The SB6121 runs slightly (average about 5 degrees F) warmer than the SB6120. 3.- Connection speeds, latency, and jitter are better with the SB6121 than the SB6120 -- and WAY faster than ANY DOCSIS 2 modems, regardless of manufacturer. Some tips I learned from using the Motorola DOCSIS 3 Modems with 2 different (D-Link DIR-655 and Netgear WNR3500L) "N"-speed Wireless Routers: The SB6120 runs coolest when mounted to a wall or other vertical surface, and spaced approximately 1/2-inch away from the surface. This allows an adequate air flow that's necessary to keep the Modem cool. Mounted with the wires pointing straight down, the SB6120 runs at about 95 degrees F in a 78 degree room when mounted away from a wall. Temperatures measured with Mastercool Infra-Red Laser Thermocouple Gun (available at desertcart). The new SB6121 is smaller than the SB 6120, and it runs a little bit warmer (98-100 F), even when mounted the same way as the SB6120. I suggest that you mount the new SB6121 1/2" away from the wall as well, but with the wires pointing straight back. Whatever you do, DON'T STACK ANYTHING on ANY Modem or Router !! Both of these devices give off heat and electrical interference, and will perform their best when spaced about 4 feet apart, which keeps the interferences from overlapping and killing the Wireless Router's range. When you get your internet connection going, go to the Motorola Modem's Home Page: Sample snapshot of my SB6121 = Cable Modem Status Signal Addresses Configuration Logs Open Source Help This page provides information about the current upstream and downstream signal status of your Cable Modem. -------------------------------------------------------------------------------- Downstream Bonding Channel Value Channel ID 49 50 57 58 Frequency 837000000 Hz 843000000 Hz 861000000 Hz 867000000 Hz Signal to Noise Ratio 37 dB 37 dB 38 dB 38 dB Downstream Modulation QAM256 QAM256 QAM256 QAM256 Power LevelThe Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading -1 dBmV -1 dBmV -1 dBmV -1 dBmV Upstream Bonding Channel Value Channel ID 3 1 2 Frequency 36100000 Hz 23300000 Hz 29600000 Hz Ranging Service ID 7425 7425 7425 Symbol Rate 5.120 Msym/sec 2.560 Msym/sec 5.120 Msym/sec Power Level 45 dBmV 45 dBmV 45 dBmV Upstream Modulation [3] QPSK [3] 64QAM [3] QPSK [2] 16QAM [3] 64QAM [3] QPSK [3] 64QAM Ranging Status Success Success Success Signal Stats (Codewords) Bonding Channel Value Channel ID 49 50 57 58 Total Unerrored Codewords 1457238562 1457238645 1457237949 1457238150 Total Correctable Codewords 17 26 23 27 Total Uncorrectable Codewords 1031 937 1682 1468 -------------------------------------------------------------------------------- Status | Signal | Addresses | Configuration | Logs | Open Source | Help © Copyright 1997-2008 It should give a snapshot of the specs for YOUR modem. You will be looking for 4 Downstream channels that read SNR @ 37-38 db and the power levels at around 0 dbmV. Upstream power levels on all 3 bonding channels should read around 45-50 dbmV. A deviation of 5 from any of these figures indicates a problem. If the Modem's signal is solid and constant, but the power level readings are 5 points off in either direction, check your OUTDOOR SPLITTERS or TAPS first, because they tend to crap out when they're exposed to heat for long periods. The operating temperatures for splitters and taps is only 140 degrees F. maximum, and that temperature is easily reached in direct sunlight, even when enclosed. Those of you who live in hot climates may notice that the Modem's downstream power levels drop off 1 or 2 points when the outside temps get up to 110 F or higher. Don't panic !! In case of rapture, dial 1-800-Oh Jesus. ;>) I found the RCA DH24SP High-Bandwidth (5-2400MHz)2-Way Signal Splitter (available at desertcart) to be an excellent handler of the high-speed signals of Cable, Satellite, and HDTV signals. It's a "2-Way" splitter, so the power flows equally in either direction, enabling MUCH higher upload speeds. If you need a TAP for unequal cable lengths, a CommScope SV-DC-6G Digital Tap worked well for me. For strong and clear Wireless range and reception, use only Category 7 (shielded) Ethernet cable (available at desertcart) between your Modem and Router, and between your Router and Main computer. Good Luck !!
Review: Lease no more - Full disclosure, I am writing this with the product just a few hours out of the box. Like most other buyers of this modem, I was annoyed having to pay Comcast the monthly modem lease fee. I finally got ticked off enough to do something about it when my leased modem became a hotspot and Comcast raised the lease rate to $10/month to boot. I compared the SB6121 modem to some others in the Arris product family. For my usage needs & level of service, this one fits the bill nicely (and at ~$65 the price is right). Having had the benefit of reading other reviews prior to installation I was aware of some potential pitfalls. The process I used was to first connect it to the cable line, power up the modem, and let it be for ~2hours (assumedly to let the firmware update and/or for Comcast to identify the new modem on the network). After the 2hr dwell, I connected the Ethernet cable from the modem to my laptop, opened IE and the Comcast setup for the new modem initiated. I had to be patient through the set up steps (took about 20 minutes to get through all of the login & initialization screens) but in the end my internet connected. After I had internet working through the laptop, I connected the modem to my wifi router. I had to power down & power up the modem and the wifi router to make the connection (first repowered the modem, and 30 seconds later powered up the wifi router) but I now had internet working through the router (wow, so far no problems). Then came the dreaded call to Comcast to get the lease fee waved... I couldn't believe the experience (it was that GOOD). I was connected to customer service in ~ 2 minutes, only spoke to one operator who took care of everything- verified the modem's ID number, waived the lease fee, and was advised where to return the Comcast leased modem. In total I only spent ~5 minutes on the phone with Comcast. I couldn't believe how painless it was. Maybe I am one of the lucky few. But the modem works as advertised... no issues with connectivity (thus far), no compromise on speed, and the set up was pretty painless.

## Features

- Compatible with Time Warner Cable, Charter, Cox, Cablevision, and more
- Not compatible with Verizon FiOS or AT&T U-verse, no longer approved by Comcast Xfinity
- Requires Cable Iternet Service, if not sure your provider is CABLE call them to confirm
- BROWN BOX models NOT VALID for this item when sold as New, should report to desertcart immediately and RETURN to Seller
- Wired modem only, does NOT include WIFI Router or VOIP Telephone adapter. Gigabit Ethernet port to connect to computer or Router for fast downloads.
- Internet speeds based on your Cable providers service - up to 172 Mbps download and 131 Mbps upload. 4 Download and 4 Upload Channels.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B004XC6GJ0 |
| Best Sellers Rank | #187,362 in Electronics ( See Top 100 in Electronics ) #165 in Computer Networking Modems |
| Brand | ARRIS |
| Color | Black |
| Compatible Devices | Personal Computer, Router, Laptop |
| Connectivity Technology | Wired |
| Customer Reviews | 4.3 out of 5 stars 11,657 Reviews |
| Data Transfer Rate | 160 Megabits Per Second |
| Global Trade Identification Number | 00612572186237 |
| Internet Service Provider | cox, optimum, spectrum, xfinity |
| Internet service provider | cox, optimum, spectrum, xfinity |
| Item Dimensions L x W x H | 6.4"L x 2"W x 8.7"H |
| Item Height | 8.7 inches |
| Item Type Name | Cable Modem |
| Item Weight | 1 Pounds |
| Manufacturer | Motorola |
| Maximum Downstream Data Transfer Rate | 172 Megabits Per Second |
| Maximum Upstream Data Transfer Rate | 132 Megabits Per Second |
| Modem Type | Cable |
| Number of Ethernet Ports | 4 |
| Number of Ports | 4 |
| Product Dimensions | 6.4"L x 2"W x 8.7"H |
| UPC | 021111531467 999997143176 163120457496 031112833194 808113025534 612572180136 707568510001 031112584188 793426726851 081258012236 804067410327 048159209707 168141495601 132017756516 172302715873 043396313620 999996719143 755263230472 151903603536 011822578936 490560200185 088020688156 885784846835 612572186237 763615975131 |
| Warranty Description | 1 year |

## Images

![Motorola SURFboard SB6121 Cable Modem (SB6121) - Image 1](https://m.media-amazon.com/images/I/61alEX8UuGL.jpg)
![Motorola SURFboard SB6121 Cable Modem (SB6121) - Image 2](https://m.media-amazon.com/images/I/61rt2foj2aL.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Smaller, Faster, and Better, too !!
*by R***S on August 4, 2012*

I was one of the first to get a Motorola SB6120 -- and was very much satisfied with the ease of set-up, the awesome speeds, the functionality, and the workmanship. But, like all electronic gizmos, they tend to crap out after a few years. When my SB6120 started dropping upstream channels, I looked to Motorola once again -- right here at Amazon -- and found the new Motorola SB6121. After checking the specs, I found that the new SB6121 Model has the latest IPV6 technology (higher bandwidth capabilities)that were not available on the SB6120. The newer IPv6 technology allows connection speeds up to 160 Mbps., against the 150 Mbps of the SB6120. IPV6 is not in common usage yet, but it will be pretty soon -- And the SB6121 will be ready with the fastest speeds available!! The new SB6121 is a super-easy set-up, and the connection speeds are fast and steady. Comparing the DOCSIS 3 SB6120 to the newer SB6121 : 1.- The Sb6121 is smaller (height and depth are smaller, width is greater). 2.- The SB6121 runs slightly (average about 5 degrees F) warmer than the SB6120. 3.- Connection speeds, latency, and jitter are better with the SB6121 than the SB6120 -- and WAY faster than ANY DOCSIS 2 modems, regardless of manufacturer. Some tips I learned from using the Motorola DOCSIS 3 Modems with 2 different (D-Link DIR-655 and Netgear WNR3500L) "N"-speed Wireless Routers: The SB6120 runs coolest when mounted to a wall or other vertical surface, and spaced approximately 1/2-inch away from the surface. This allows an adequate air flow that's necessary to keep the Modem cool. Mounted with the wires pointing straight down, the SB6120 runs at about 95 degrees F in a 78 degree room when mounted away from a wall. Temperatures measured with Mastercool Infra-Red Laser Thermocouple Gun (available at Amazon). The new SB6121 is smaller than the SB 6120, and it runs a little bit warmer (98-100 F), even when mounted the same way as the SB6120. I suggest that you mount the new SB6121 1/2" away from the wall as well, but with the wires pointing straight back. Whatever you do, DON'T STACK ANYTHING on ANY Modem or Router !! Both of these devices give off heat and electrical interference, and will perform their best when spaced about 4 feet apart, which keeps the interferences from overlapping and killing the Wireless Router's range. When you get your internet connection going, go to the Motorola Modem's Home Page: Sample snapshot of my SB6121 = Cable Modem Status Signal Addresses Configuration Logs Open Source Help This page provides information about the current upstream and downstream signal status of your Cable Modem. -------------------------------------------------------------------------------- Downstream Bonding Channel Value Channel ID 49 50 57 58 Frequency 837000000 Hz 843000000 Hz 861000000 Hz 867000000 Hz Signal to Noise Ratio 37 dB 37 dB 38 dB 38 dB Downstream Modulation QAM256 QAM256 QAM256 QAM256 Power LevelThe Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading -1 dBmV -1 dBmV -1 dBmV -1 dBmV Upstream Bonding Channel Value Channel ID 3 1 2 Frequency 36100000 Hz 23300000 Hz 29600000 Hz Ranging Service ID 7425 7425 7425 Symbol Rate 5.120 Msym/sec 2.560 Msym/sec 5.120 Msym/sec Power Level 45 dBmV 45 dBmV 45 dBmV Upstream Modulation [3] QPSK [3] 64QAM [3] QPSK [2] 16QAM [3] 64QAM [3] QPSK [3] 64QAM Ranging Status Success Success Success Signal Stats (Codewords) Bonding Channel Value Channel ID 49 50 57 58 Total Unerrored Codewords 1457238562 1457238645 1457237949 1457238150 Total Correctable Codewords 17 26 23 27 Total Uncorrectable Codewords 1031 937 1682 1468 -------------------------------------------------------------------------------- Status | Signal | Addresses | Configuration | Logs | Open Source | Help © Copyright 1997-2008 It should give a snapshot of the specs for YOUR modem. You will be looking for 4 Downstream channels that read SNR @ 37-38 db and the power levels at around 0 dbmV. Upstream power levels on all 3 bonding channels should read around 45-50 dbmV. A deviation of 5 from any of these figures indicates a problem. If the Modem's signal is solid and constant, but the power level readings are 5 points off in either direction, check your OUTDOOR SPLITTERS or TAPS first, because they tend to crap out when they're exposed to heat for long periods. The operating temperatures for splitters and taps is only 140 degrees F. maximum, and that temperature is easily reached in direct sunlight, even when enclosed. Those of you who live in hot climates may notice that the Modem's downstream power levels drop off 1 or 2 points when the outside temps get up to 110 F or higher. Don't panic !! In case of rapture, dial 1-800-Oh Jesus. ;>) I found the RCA DH24SP High-Bandwidth (5-2400MHz)2-Way Signal Splitter (available at Amazon) to be an excellent handler of the high-speed signals of Cable, Satellite, and HDTV signals. It's a "2-Way" splitter, so the power flows equally in either direction, enabling MUCH higher upload speeds. If you need a TAP for unequal cable lengths, a CommScope SV-DC-6G Digital Tap worked well for me. For strong and clear Wireless range and reception, use only Category 7 (shielded) Ethernet cable (available at Amazon) between your Modem and Router, and between your Router and Main computer. Good Luck !!

### ⭐⭐⭐⭐⭐ Lease no more
*by M***3 on January 17, 2015*

Full disclosure, I am writing this with the product just a few hours out of the box. Like most other buyers of this modem, I was annoyed having to pay Comcast the monthly modem lease fee. I finally got ticked off enough to do something about it when my leased modem became a hotspot and Comcast raised the lease rate to $10/month to boot. I compared the SB6121 modem to some others in the Arris product family. For my usage needs & level of service, this one fits the bill nicely (and at ~$65 the price is right). Having had the benefit of reading other reviews prior to installation I was aware of some potential pitfalls. The process I used was to first connect it to the cable line, power up the modem, and let it be for ~2hours (assumedly to let the firmware update and/or for Comcast to identify the new modem on the network). After the 2hr dwell, I connected the Ethernet cable from the modem to my laptop, opened IE and the Comcast setup for the new modem initiated. I had to be patient through the set up steps (took about 20 minutes to get through all of the login & initialization screens) but in the end my internet connected. After I had internet working through the laptop, I connected the modem to my wifi router. I had to power down & power up the modem and the wifi router to make the connection (first repowered the modem, and 30 seconds later powered up the wifi router) but I now had internet working through the router (wow, so far no problems). Then came the dreaded call to Comcast to get the lease fee waved... I couldn't believe the experience (it was that GOOD). I was connected to customer service in ~ 2 minutes, only spoke to one operator who took care of everything- verified the modem's ID number, waived the lease fee, and was advised where to return the Comcast leased modem. In total I only spent ~5 minutes on the phone with Comcast. I couldn't believe how painless it was. Maybe I am one of the lucky few. But the modem works as advertised... no issues with connectivity (thus far), no compromise on speed, and the set up was pretty painless.

### ⭐⭐⭐⭐ Takes Some Perseverance, Signal Probs on Start Up
*by D***Y on January 12, 2013*

this is my latest review: I have had this now for quite some time. Turns out the docsys 3 is very sensitive and shuts itself down when overloaded. TW sent their best guy out finally. Turns out especially in heavy traffic ares it needs a "splicer" which throttles down the incoming. Since they have attached the splicer I've had no problems at all! this was my second review: I had a lot of trouble to begin with. Kept on dropping signal. Time Warner had to come out and replace all my connectors. Doc sys 3 is more demanding than doc sys 2 in terms of all the connectors being in sync it seems. Once that was done all has worked quite well. I have updated my stars on this to 3. Its a good product. But there is caveats with the DocSys 3s overall. Especially if you are in a highly trafficked area and share outgoing cable line such as in an apartment building. Doc sys 3's have more bands, thus require more band width. TWC has done some fixing around here which has appeared to strengthen by connection. I bought the Zoom 5431 and couldnt get it to handshake across all bands. Ended up sending it back and keeping the SB 6121. The Zoom has 12 bands: 8 + 4. The Motorola 8 bands. On digging deeper I found that all of the doc sys 3's have this problem. I talked to Motorola. She says firmware is pushed through the Provider. And in many cases Doc Sys 3 is still a relatively new system for them. Provider controls almost everything in the box. If some update hasnt made it through properly you can experience problems. I am in an apartment building and share through up on the roof. Since reconnecting the sb6121 I am having much less problems with it. But, unlike the single band doc sys 2's I have become resigned to the fact that buying into more bandwidth also makes my modem a more complicated and demanding piece of machinery vis a vis the connection and that I will, probably at least once a day, time out until the provider perfects the firmware. I will say that when the sb6121 reboots it reconnects across all bands very nicely. And when I reset to factory default, and waited the necessary half an hour before rebooting (resetting gets all its firmware configs from the provider, you might even have to call and ask them to push it through again, according to motorola) my box has been working much better. I'd say buying into docsys 3's be prepared for a little more work on getting it set up. ORIGINAL REVIEW: If you are a time warner customer think twice. I am a turbo customer in a heavy traffic urban setting. The modem is constantly timing out. If you look up SB6121 online re bonding values you will find that there are many many customers who share this same issue. More than any other modem. It appears to be extremely sensitive to noise. I have researched the issue for hours, there does not appear to be a fix. This issue, of constantly timing out, is I believe a docsis 3 problem. The docsis 3's have multiple bands, which "bond," creating a cross tunnel that supposedy keeps a more stable connection than docsis 2s which have only one band and do not bond. If one band is bonding on a docsis 3 system the theory is it should work without any interruption problems. But, with this modem, when one of the bands stops connecting, it essentially freezes as it tries to recalibrate its footing. This can happen as much as up to every 10 minutes. So I am returning for the Zoom 5341. It is also a docsis 3 system, but seems according to the lack of complaints online (1 versus 100) to be able to churn its way through the timeouts without dropping the connection. I will let you know if it can handle a heavy trafficked neighborhood.

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*Product available on Desertcart Cyprus*
*Store origin: CY*
*Last updated: 2026-02-23*