Cable modem (newish tp-link) loses connection 1 to 2 times a day. A reset fixes it, but it really eats into my daily routine to have to take care of this, and it has dropped during important Zoom calls and other work meetings over the past year. I'm pretty sure this is on Cox's end, since this same cable modem worked perfectly with no issues at my last address (also Cox). I checked the system logs, and found multiple iterations of the following when the connection dropped this morning (MAC addresses deleted): Tue Mar 22 06:47:43 2022 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC= Tue Mar 22 06:47:39 2022 Critical (3) REG RSP not received;CM-MAC= Tue Mar 22 06:47:08 2022 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC= Tue Mar 22 06:47:06 2022 Critical (3) No UCDs Received - Timeout;;CM-MAC= Tue Mar 22 06:46:49 2022 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC= Tue Mar 22 06:46:45 2022 Critical (3) Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC= Post-reset, everything's good. Current power levels range from downstream -18.5 dBmV to -17.8 dBmV with SNR 30.7 dB to 31.6 dB, and upstream 57.0 dBmV. I've tried calling tech support in the past, but the advice has usually defaulted to "reset your modem"...which isn't sustainable for me anymore at this rate. Any advice would be appreciated. Should I record power levels when the connection drops again and post here?

Up the wall. If this building has always been an apartment, I'd think each unit, to include the landlord, would have a separate connection. Somewhere near your building is a neighborhood node. It could be a green box, cabinet or pedestal. If its distance is far, there would be one thicker coax connecting at a smaller box bolted onto your building, or if it's closer, there would be multiple RG6 cables connecting at 3-4 bolt-on boxes. At this point (demarcation point), 3-4 cables would run to each apartment. You'd have to imagine the location of this demarc in reference to your wall plate. Is its location upward? However, this isn't an exact assessment because the cables from the demarc could run into the attic and then downward into each apartment. It just depends how easier it was to distribute cables. RG6 vs. RG59. RG6 is the standard nowadays and it's noticeably thicker than RG59 with 1/16". This may take a little coordination on your behalf. I'd ask your neighbors about their connections. If it's also bad, the landlord should call a tech. If it's good, you should ask their type of modem: DOCSIS 3.0 vs. 3.1. I wouldn't replace your D3.0 yet but have your landlord call a tech because this tech would need free access to the attic, utility room, garage, etc to test for noise, faulty splitters, chaffing, etc. "Like clockwork" is interesting because it could mean peak hours for your building.

Yes, it'll still work but I tripped on "newish." As Mouth suggested, snoop along your coaxial cable for a splitter. A splitter is just a connection device, piece of hardware. Also check behind your wall plate for splitters. You may just have to replace it. Cheaper than a tech if it fixes.

Sorry about describing a splitter. Yeah, in-house stuff to check before calling a $$$ tech. If it's an outside problem, you shouldn't have to pay for a Cox problem. Most problematic are splitters and perhaps older or damaged cable. This stuff you can replace yourself. If you read real close on your cable, you'll find a specification, such as RG-59, RG-6, etc.

What's the make and model of your TP-Link? I agree your power looks out-of-spec, your peak SNR looks low and if Up is 57 dBmV, it's at the brink of no connectivity.

I'm not suggesting it's your modem, but the approved TP-LINK modems on the Cox list are DOCSIS 3.0. www.cox.com/.../cox-certified-cable-modems.html

Forum Discussion

johnny213

New Contributor II

3 years ago

Cable modem dropping connection 1 - 2 times a day

Cable modem (newish tp-link) loses connection 1 to 2 times a day. A reset fixes it, but it really eats into my daily routine to have to take care of this, and it has dropped during important Zoom calls and other work meetings over the past year. I'm pretty sure this is on Cox's end, since this same cable modem worked perfectly with no issues at my last address (also Cox).

I checked the system logs, and found multiple iterations of the following when the connection dropped this morning (MAC addresses deleted):

Tue Mar 22 06:47:43 2022	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=
Tue Mar 22 06:47:39 2022	Critical (3)	REG RSP not received;CM-MAC=
Tue Mar 22 06:47:08 2022	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=
Tue Mar 22 06:47:06 2022	Critical (3)	No UCDs Received - Timeout;;CM-MAC=
Tue Mar 22 06:46:49 2022	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=
Tue Mar 22 06:46:45 2022	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=

Post-reset, everything's good. Current power levels range from downstream -18.5 dBmV to -17.8 dBmV with SNR 30.7 dB to 31.6 dB, and upstream 57.0 dBmV.

I've tried calling tech support in the past, but the advice has usually defaulted to "reset your modem"...which isn't sustainable for me anymore at this rate.

Any advice would be appreciated. Should I record power levels when the connection drops again and post here?

Bruce
Honored Contributor III
3 years ago
What's the make and model of your TP-Link?

I agree your power looks out-of-spec, your peak SNR looks low and if Up is 57 dBmV, it's at the brink of no connectivity.
Bruce
Honored Contributor III
3 years ago
I'm not suggesting it's your modem, but the approved TP-LINK modems on the Cox list are DOCSIS 3.0.

www.cox.com/.../cox-certified-cable-modems.html
- johnny213
  New Contributor II
  3 years ago
  Yup; I checked the approved list a few years ago. I have a 7610, and it looks like it's still approved.
  - Bruce
    Honored Contributor III
    3 years ago
    Yes, it'll still work but I tripped on "newish."
    
    As Mouth suggested, snoop along your coaxial cable for a splitter. A splitter is just a connection device, piece of hardware. Also check behind your wall plate for splitters. You may just have to replace it. Cheaper than a tech if it fixes.
Bruce
Honored Contributor III
3 years ago
Just a long shot, you may try factory-resetting the modem. There is a difference between your "reset" in your post and a reboot. You can also reset via your Cox account. A reboot just reboots the modem as is, but an online reset does other stuff.

So...there are 3 types: a reboot, an online reset & a factory reset.

Search T4:

www.cox.com/.../TP-LINKTC7610_UserGuide.pdf

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Cable modem dropping connection 1 - 2 times a day

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