Cable Modem: Started Unicast Maintenance Ranging - No Response received - T3 time-out

Here's some additional information that might be of use:

Startup procedure

Downstream Bonded Channels

Upstream Bonded Channels

Downstream OFDM Channels

The upstream power levels are too high. This suggests a problem between your equipment and Comcast's network. Network connection problems are often due to poor coax connections or damaged coax cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you can't find the problem or you'd rather have Comcast take care of it, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. If they can't fix the problem remotely (unlikely), insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Hi @BruceW,

Thanks for the reply. Here's the steps I've taken since yesterday:

1. Replaced my cable modem with an older model I had in storage (Netgear CM500V)
2. Removed a splitter between the wall and the cable modem
3. Replaced the coaxial cable between the wall and the cable modem.

The good news is that things seem more stable. Yesterday I ran a speedtest and had jitter around 200ms and packet loss around 30%! Today's jitter is 3.5ms with 0 packet loss.

Now, as far as the upstream power levels - do these still seem too high?

Upstream Bonded Channels

If so, then that means it's somewhere between the wall and the street, correct?

Thanks again for your help!

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@CaptainHammer wrote: ... do these still seem too high? ... If so, then that means it's somewhere between the wall and the street, correct?

Upstream power levels are better, but uncomfortably close to the max. I like to see them between 40 and 45, but these may be OK if they are stable.

Since you've replaced the modem and the cabling to the wall jack then yes, if there is still a problem it should be in the wall jack or beyond.

Bottom line: is it working as it should? If so, good! If not, more needs to be done.

Good luck!

Hey @BruceW,

It's been a few days and things seem to be more stable with the older modem and different cables. However, I just had to power cycle the modem as the internet all of a sudden stopped working. This wasn't slow speeds - it was no speeds, no connection.

Could it be related to the previous problems, or just a small hiccup? I've got another modem arriving in a few days and will try that out. I'm just starting to get to my wits' end - with me doing remote work and my son doing online classes, we rely on uptime pretty heavily. Think I should call Xfinity and get a technician out to check the lines?

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@CaptainHammer wrote: ... I just had to power cycle the modem ... Could it be related to the previous problems ...

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Can you post the current power level and SNR readings? If they're not in spec and you can't correct them, then yes, have Comcast out to take a look.

Here's the current power level and SNR readings. Had an uptime of about 10 hours:

Downstream Bonded Channels

Upstream Bonded Channels

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@CaptainHammer wrote: Here's the current power level and SNR readings. ...

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Upstream power levels are still uncomfortably close to the max of 51. Again, if your Internet service is not working as it should and you can't fix it, have a Comcast tech come out.

I'm now losing the lock status on some of the upstream bonded channels with the associated power levels dropping to 0.0 dBmV. Technician is scheduled for tomorrow.