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Arris SB6121

details: SURFboard DOCSIS 3.0 Cable Modem
hardware type: Cable Modem
date added: 2010-08-08
updated: 2023-01-14
Utilizing the power of DOCSIS 3.0, the SB6121 enables channel bonding of up to four downstream channels and four upstream channels, which allows an operator to offer their customers advanced multimedia services with data rates of over 100 Mbps in each direction.

The SB6121 features a 10/100/1000Base-T Ethernet (RJ-45) port, as well as intuitive, easy-to-read front-panel operational status LEDs. Operators can optionally activate dual colored LEDs for their customer to have visual verification of bonded channels and GigE link use.

This modem supports IPv4 and IPv6 to expand network addressing capabilities and uses AES traffic encryption.

As part of Motorola DOCSIS 3.0 Ultra-Broadband family of products, the SB6121 includes an enhanced tuner that supports up to a 1 GHz downstream input, which allows operators to increase the frequency spectrum for deployment of new high-value services, such as bandwidth on-demand, commercial services, interactive gaming, and IPTV, to their customers.
 SB6121 Features
 Availability: currently available
 LAN / WAN Connectivity
 WAN throughput: 222 Mbps
 WAN throughput upstream: 131 Mbps
 WAN ports: 1
 WAN port(s) type: Coax F-connector
 LAN ports: 1
 LAN ports type: Gigabit Ethernet (RJ-45)
 LAN ports auto cross-over: yes
 Cable Modem
 DOCSIS compliance: DOCSIS 3.0
EuroDOCSIS 3.0
 DOCSIS channels (down x up): 4x4 (152 Mbit/s)
 Device Management
 Default IP address:
 Administration: Quick Setup Wizard
 Firmware upgradeable: yes
 Diagnostic functions: yes
 Misc hardware info
 Chipset: Intel Puma 5
 SNMP support: SNMP v.2, SNMP v.3
 IPv6 support: yes
 Product page:
 Quick Install Guide:

Please use the Add Comment function below to review devices you have used (please be descriptive). If you find an error in our database, or have additional information about the product, please
  User Reviews/Comments:
by bigbore - 2010-10-11 21:55
so where on earth can you buy one of these???????? No one has them for sale
by anonymous - 2011-02-08 16:52
Buy it on Ebay like it did!
by Reader - 2011-10-08 12:17
Can I say I hate it when someone reviews a modem badly because they can't find it? That doesn't help the rest of us decide whether or not to buy it at all.

I have mixed reviews, myself. One friend has had great speed, 100% uptime, no problems for over a year. The other had theirs die around 9 months post-purchase.
by Swag - 2011-11-30 16:50
mine lasted for 3 mths. Regretted wasting my money on this pdt
by kungfooo - 2011-12-27 17:55
I am very happy with it. I bought mine at Best Buy. I am on Cox and I am getting over 100 mb down. Unfortunately they squeeze the up and I am stuck at 5 mb up. No problems so far.
by ToddFL - 2012-02-05 15:30
DHCP very unreliable and advanced configuration not available. DO NOT BUY this modem if you need to define DHCP reservations. Attempted to use with a D-Link switch and the DHCP (which is limited to 32 addresses for some resason) would only assign one.
by ZAXXON - 2012-07-06 07:34
by anonymous - 2016-02-01 14:24
I have used this modem for 3 years (bought at Best Buy) with excellent results. I have a home wireless network and the modem services my computers, TV & Internet-connected Blu-ray player as well as devices such as smartphones & iPads/tablets. OOKLA speed tests are consistently above 85 mbps. Even now (as it is not a new model) I would recommend it to anyone without hesitation. Usually, if you have a problem it's not that you have a crappy modem or router, you just need to get into your manufacturer's Knowledge Base articles for the product because you will often find your exact problem and solution there.
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