I have a SB6121 modem (has both Arris and Motorola logos on it). Yesterday the speeds were horrible on Comcast/Xfinity. I rebooted the router and the modem. No joy. I did several other things...but to make a long story short...I ended up plugging up my laptop directly into the modem to isolate the issue. Again same results as before...speeds were in the 200-300 kBps range down rather than the 70MBps I'm used to getting. There is some construction in my neighborhood where AT&T is laying fiber on the same right-of-ways as the cable runs..so it's possible that AT&T cut the cable or damaged it.

I have a new Arris SB6190 that I bought today..but I was wondering if anyone knew of anything I can do before I go to swapping parts blindly. I have the logs..but the numbers look borderline to me: power level and SNR...

Any help is appreciated.

2 ...

Report Post

Posted by tgrgrd00

Kenner, LA

Member since Jun 2004

8509 posts

Posted on 2/24/17 at 1:32 pm to NASA_ISS_Tiger

I would contact Comcast to see if there are any known issues before I would think of messing with my hardware.

1 ...

Report Post

Posted by NASA_ISS_Tiger

Huntsville, Al via Sulphur, LA

Member since Sep 2005

7981 posts

Posted on 2/24/17 at 2:04 pm to tgrgrd00

Ah yes...Comcast...and I talked to "Paramjeet". I honestly believe my Hindi is better than his/her English. I'll call again...and hopefully I can get someone who speaks English as their first language.

0 ...

Report Post

Posted by Spock's Eyebrow

Member since May 2012

12300 posts

Posted on 2/24/17 at 4:27 pm to NASA_ISS_Tiger

I doubt your SB6121 has suddenly gone bad. I would call your provider and complain before doing anything, like buying a new modem.

As for your new SB6190, that modem has a well-known problem with latency spikes due to a bug in the Intel Puma chipset it uses. The good news is, Arris says Intel has provided them with a fix. The bad news is, they haven't rolled it out yet, and your provider may not roll it out right away when it does become available. Much more here, in the thread where I learned about it:

LINK

2 ...

Report Post

Posted by NASA_ISS_Tiger

Huntsville, Al via Sulphur, LA

Member since Sep 2005

7981 posts

Posted on 2/25/17 at 11:38 pm to Spock's Eyebrow

Just to close the loop on this. Seemed like it magically fixed itself...I left the 6121 unplugged all day came home and wanted to make sure the line hadn't been cut so I turned on the only cable tv in the house (we are on Direct TV for our TV's we watch)....the Comcast box was just part of a deal...that TV worked fine...cable showed video and all channels worked so I knew there was no line cut. Went to modem with laptop directly plugged in again..and the signal strength on the D/S leg had dramatically improved. As a result, the bandwidth returned to nominal values. Other people reported later last night they were having issues as well, so I still have the 6190, but I won't open it until I need to. Currently trying to force a heat condition where the modem is located (in a coat closet with the door closed and light is on (incandescent)...so in case the modem is overheating I'm trying to recreate the problem. So far 24 hours no issue. Temp in closet around 80 degrees only as measured with thermocouple.

0 ...

Report Post

Posted by seawolf06

Member since Oct 2007

8159 posts

Posted on 2/27/17 at 12:17 pm to Spock's Eyebrow

quote:
I doubt your SB6121 has suddenly gone bad.

I've had a modem go bad what seemed like overnight. The SB6141 utilizes 8 channels while the SB6121 only has 4. My modem lost half the channels and whether it happened all at once or over time, I don't know. However, losing just one channel out of 8 only has a 12.5% impact while losing one out of four has a 25% impact.

Page 1