U

Sunday, February 25th, 2024 4:10 AM

Intermittent internet drops (5 minutes at a time); very bad SNR on 3 channels

For the past week, I have been having my internet service drop for about 5 minutes at a time, a few times a day. I replaced my equipment in hopes this would solve it, but have seen no fix.

I notice that I have very low signal quality on 3 channels. This is an SB6190 modem which is a 32x8 device.

On my 32 bonded channels, I'm seeing SNR of 40 dB (+/- 1 dB) on almost all of them. But channels 33-35 are very low quality. Channel 33 (627 MHz) is showing as Not Locked; Channel 34 (633 MHz) is showing 37.09 dB, with 168,000 Corrected and 39,000 Uncorrectables; Channel 35 is showing 31.92 dB, 134,000 Corrected and 79,000 Uncorrectables.

Is it reasonable to think these problems are related? I am wondering if 3 poor channels may cause the connection to be more fragile and therefore drop and take a few minutes to re-establish. Is this an issue with my end (cabling, perhaps) or is it possible that this is equipment malfunctioning on Xfinity's side?

I also see in the event log a large number of "Lost MDD Timeout" and "RCS Partial Service" errors listed, even when the internet is working.

Also, I don't think this is relevant, but I'm only seeing 5 upstream bonded channels, where I expected that my 32x8 modem would show 8.

Contributor

 • 

168 Messages

2 months ago

@user_y55dvg - depends how comfortable you are troubleshooting, you could start with the steps in this Post or another webpage if you wish.

2 Messages

@user_noname​ Thank you. I plotted my reported downstream dBmV over all the frequency channels and produced this plot:

Is this level of variance enough to constitute a problem? There's a definite drop around the 600-650 MHz range, but I'm not sure if the magnitude of the drop (about 1.5 dBmV) is enough to identify this as the source of the issue.

Contributor

 • 

168 Messages

@user_y55dvg - I don't think it is, as my current variance is from -0.4dBmV to -4.2dBmV and it fluctuates through out the day.

Below is the chart of my current downstream -

(edited)

Expert

 • 

103.3K Messages

2 months ago

@user_y55dvg wrote;

but I'm only seeing 5 upstream bonded channels, where I expected that my 32x8 modem would show 8.

That's normal. Comcast does not yet offer 8 channels in any market areas. 3-6 is typical. It all depends on the capacity needs of any given local area. It gets decided by their engineering / capacity planning departments on how many are needed to handle the utilization.

Contributor

 • 

168 Messages

@user_y55dvg - agreed with @EG , the number of upstream channels is controlled by Xfinity and haven't seen them configure 8 upstream bonded channels.

Expert

 • 

103.3K Messages

2 months ago

@user_y55dvg wrote; 

"Channel 35 is showing 31.92 dB"

That's far out of spec ! It appears that you have a pretty severe suckout going on / noise ingressing into the line(s) somewhere at that range of frequencies. If you can't find anything obvious, you may want to consider getting a tech out to investigate this one. The problem may lie beyond your premises.

forum icon

New to the Community?

Start Here