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Motorola SB6120

details: DOCSIS/ Euro DOCSIS 3.0 Cable Modem
hardware type: Cable Modem
date added: 2009-08-17
updated: 2023-01-14
Motorola's easy-to-use SB6120 SURFboard eXtreme Cable Modem unlocks the potential of offering innovative high-bandwidth data and multimedia services to customers. Utilizing the power of DOCSIS 3.0, the SB6120 enables channel bonding of up to 4 downstream channels and 4 upstream channels - which allows an operator to offer their customers advanced multimedia services with data rates of well over 100 Mbps in each direction. It supports IPv4 and IPv6, Advanced Encryption Services (AES), and all other DOCSIS 3.0 standards.

» Forums search for Motorola SB6120
 SB6120 Features
 Availability: currently available
 Street price: $100
 Warranty: 1 year(s)
 LAN / WAN Connectivity
 WAN throughput: 172 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 1.0
EuroDOCSIS 3.0
 Cable Diagnostics: yes
 VPN Encryption: AES (128-bit)
 Device Management
 Default IP address:
 Default admin username: admin
 Default admin password: motorola
 Administration: Web-based (LAN)
Quick Setup Wizard
TFTP (RFC 1350)
 Firmware upgradeable: yes
 Diagnostic functions: yes
 Misc hardware info
 SNMP support: SNMP v.2
 IPv6 support: yes
 Product page:

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 bk55 - 2011-02-17 23:55
All that’s wrong with the Motorola SB6120:

-- It takes forever to initialize. At least 4-5 times longer than the SB5101.

-- A power cycle can take 5-30 min, per User Guide. Come on, Motorola! Don’t you feel foolish to build a small piece of network equipment that can take up to 30 min. (THIRTY!!) to reset?
(As an aside. I followed the instructions in the User Guide for power cycling the modem (pg. 26) and waited for all the LEDs to turn solid ON. After 50 min, not even the first LED (other than the power LED) has turned solid.)

-- The documentation is completely out of date.
-- The User Guide was written in 2008!
-- It knows nothing about Windows 7. I.e., all references to MS OSs end with Vista.
-- It instructs to configure the TCP window size (pg. 25) and sends the user to Motorola’s consumer support web site. First, it does NOT take the user
directly to the required instructions but only to the general support site.
Then their FAQ has never heard of a ‘TCP window size’.

-- It is NOT plug ‘n play. Sometimes it can be activated without a hitch; many times it will not come online. It simply resets itself over and over and over (the LEDs cycle through).

Apparently, from reading many entries on several user forums, it seems to be exceedingly touchy about power levels, the specs for which are much tighter than for the SB5101. Which touchiness has created, and continues to create, a BIG problem for users, at least some of them, on the Comcast network. Motorola blames the problem on Comcast.
-- However, users on other carrier networks experience the same problem.
-- Motorola blames it on the DOCSIS 3.0 specs.
-- Other DOCSIS 3.0 cable modems do NOT have a problem with excessive power level sensitivity.

I think it’s ridiculous that after nearly 2 years on the market, so many Comcast customers still have to waste hours of their time researching and troubleshooting the -- supposed -- power level problem, with Comcast insisting they see no problem and the customer stuck in the middle.

Other reasons for the continuous reset have been reported as:
-- duplicate MAC addresses, and/or
-- outdated firmware. The kicker with old firmware is that there is nothing you, as the user, can do about it. It’s the ISP who downloads firmware upgrades. BUT, they can only do that once the modem has synced up … the inability to do so is the problem in the first place. Now what is the user supposed to do?
-- To know whether one has the latest firmware, one must know what it is, which is a piece of information not to be found on Motorola’s site.

-- The remote management system is highly inadequate. It provides little information, allows few configuration changes, and the “Help” function is useless. It tells you, e.g., that the “Signal” section gives you information about the signal, without any explanation of what the recommended values should be, or how to change them, or IF it’s even possible to change them.

Users have reported that after inserting splitters, on a trial and error basis, they were able to reduce the power level sufficiently for the modem to go online. Come on! I’m supposed to go out and buy splitters and experiment with them, on something that claims to be the latest and greatest technology? Yes, implementing DOCSIS 3.0 in more complex than it was for DOCSIS 2.0, but Motorola is unable to build a stable and/or adjustable power interface?

So, unless you are either (1) one of the lucky ones when the modem can be activated without problems, or (2) you are willing to spend many hours in the attempt, DON’T BUY IT.
by alphadelta220 - 2011-03-03 03:23
i dont get it power cycle took less then 1 minute for me i don't known what you did wrong but you did. i am not trying to bs on you, i want to understand your problem with that modem since i got none
by anonymous - 2011-03-23 12:32
hook it up called comcast and that was that.
by Philip - 2011-06-09 09:34
I'm currently using the SB6120. It's been stable for me, activated, synced and took firmware updates from the headend without a hitch. Signal levels and throughput actually improved a small bit over the older Arris modem it replaced.

Supports DOCSIS 3.0 and EuroDOCSIS 3.0, channel bonding, etc. Haven't had any issues with it.
by anonymous - 2011-12-31 20:07
As others have said, this modem reboots in less than a minute. Is extremely stable and super fast. I get powerboost spikes of 120 Mbps, and 70-90 Mbps normal throughput. Downloading very large chunks of data and it is a solid line across the board with no hiccups what so ever. Just a solid modem. Ive had it connected for roughly a year now and its only gone down once, and that was when Comcast upgraded my neighborhood to D3.
by AnthonyG70 - 2012-04-07 19:39
been using the device for a year now, and extremely satisfied. i purchased at local electronic retailer, brought it home, called cable company and gave them required info and was set in queue for activation. once activated it has remained consistant.

i use my connection for gaming, streaming media (smartTV) and home business use. i have also used openvpn, terminal services, citrix and cisco vpn connections with no hitches. i have always been satisfied with motorola cable modems, and the speed and stability enhancements of a docsis 3 device have been phenominal.

a side note, not related to modem, some cable companies put a filter on the cable data line. i noticed when the filter got hot, while in the sun (condo w/multiplexor setup outdoors) it caused data drops on occassion. i requested the cable company remove the filter, as it was only there to stabilize the line by filtering out uneeded frequencies. once removed, there have been zero issues with connection. the modem seems to have good internal filtering, which was probably not the case for older docsis 2 devices.
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