Motorola SURFboard SB5101U - Disconnecting/Reconnecting


Let me start by saying, I'm a TWC "light internet" customer, I just check email and occasionally play on a tablet. So I never upgraded to the latest&greatest docsis 3 modem... because I thought that was 'overkill' for my needs.

I have a Motorola SURFboard SB5101U which is Disconnecting/Reconnecting
I understand this is an old modem, if my problem is evidence that I should replace my modem... just let me know! But I was hoping it would be something obvious for someone techie like "dude, someone is trying to hack you" or "that DHCP error, you just need to ipconfig /release /renew"

Another forum recommended checking the modem logs here so I checked that.
The log page seems to be displaying the same five errors over and over again.


1970-01-01 00:00:08



Ethernet link up - ready to pass packets

2018-03-07 08:30:52



Modem Is Shutting Down and Rebooting...

2018-03-07 08:30:52



Received Response to Broadcast Maintenance Request, But no Unicast Maintenance o

2018-03-07 08:30:19



Started Unicast Maintenance Ranging - No Response received - T3 time-out

1970-01-01 00:00:14



DHCP WARNING - Non-critical field invalid in response ;CM-MAC=redactedMacAddress;


 Any ideas what would fix this?


Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

just to be clear, it's an actual mac address, the same one every time, I just wrote 'redactedMacAddress' because I'm paranoid... yes, paranoid about hackers
Robot surprised

Community Manager

Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting



Welcome to the Forums and I apologize for any service issues.  I was able to locate your account based on your registration information.  While I am not seeing any evidence of you being hacked, I am seeing T3 and T4 errors, as well as signal issues that need attention from a service call.    We can set up a service call for you if you contact us at this private message link.   


If you prefer, you can also contact us directly.   Please contact us at: 


Spectrum-Social Media Customer Care




Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

Please post your signal levels page as well.


Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

get a new modem from spectrum, that ones a single ch obsolete one.. I'll bet you also have a coaxial problem due to bad connections and too many splitters... A new modem will work worst as it needs cleaner signal

It's going to take a service call.

Post the level page, need to see how bad it is...




Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

Is this the right page?
It says: 

The Signal Page provides information about the connection between the Cable Modem and the cable company


Frequency633000000 Hz
Signal To Noise Ratio33.7 dB
Power Level-2.8 dBmV
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading


Channel ID20
Frequency37000000 Hz
Power28.7 dBmV

Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

Get a new modem from them, that's an obsolete docsis 2 one and is stuck on a single channel  which can be easily interfered with.. Those are going for a couple dollars on ebay, lol, hope you're not paying $5 a month rental.

It could be a bad modem, the s/n looks low, that might be okay since docsis 1-2 works at a 30 dB s/n whereas docsis 3-3.1 needs 34 dB s/n to be somewhat reliable.

Repost the new sig pages with the new modem



Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

Just wanted to close the loop on this.


I bought a new Motorola SB6141 modem, but was still having a significant amount of disconnects. So I placed a service call, the tech seemed very knowledgeable.

The signal was low even at the pole, because "I'm at the end of a run" but he didn't seem concerned by that, in my house - he replaced the coaxial cable and the splitter with one which will work in a lower range and in 24 hours, I haven't had a single disconnect!

Lead Moderator

Re: Motorola SURFboard SB5101U - Disconnecting/Reconnecting

Good morning!


Glad to hear this appears to be resolved. I have marked this as the solution. If you find that this is not the case please let us know so that we can remove the flag.


Have a great day!

Julia R.
Spectrum-Social Media Customer Care
Lead Moderator-Community Forums