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Random drops and modem disconnects - How to get a competent response from support?

Let me start this off by saying that I am livid with Cox support and the inability to get a competent response. I am a Network Engineer with 2 decades of experience and literally spend every day configuring/debugging networks and equipment, from server applications down to the network packet bit level. I have not found any issue with my equipment.

For the past couple weeks my home Cox Internet connection has had random drops and modem disconnects throughout the day. For the past 3 days it has been horrible. My far less technical neighbor confirms "it has gone to $#%7". When it is working, there is no issue and modem signal levels are about as good as you can get. When it drops one of two things happen:

1) Loss of all internet traffic for 15sec to 20min - Modem shows as connected with 42+dBm SNR and little to no errors. Unable to ping the Cox headend gateway from my router. Unable to renew or get a DHCP address from Cox on my router. I can see ARP requests and occasional DHCP responses to other customers, but no response to my DHCP requests. At some point it will suddenly start passing packets again without any changes. Resetting the modem does not fix it.

2) Loss of all internet traffic (modem shows as connected) followed by the modem losing sync a minute or two later and flipping between "provisioning" and "access denied" for the next 2-20min. Sometimes it will provision and appear connected for a few minutes, but I can not get DHCP or internet traffic.

This has to be affecting my entire neighborhood and my neighbor confirms the same dropouts. I finally call in to open a ticket/find out an ETR and Cox Support wants to know what TV I am streaming with... Cox Support wants to know if my computers are hardwired or wireless... Cox Support wants me to reboot my computer... Cox Support wants to know how I know my computer can't get DHCP... None of these have anything to do with my ROUTER connected the the Cox cable modem, not getting DHCP or packets from Cox.

The only answer I have gotten out of Cox is that my modem looks fine and if I agree I can have a Cox Tech come out and "test" my equipment for $75/hr. How do you get a competent response out of Cox Support when the problem is upstream of the modem? This is likely a Cox headend or backhaul issue...

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  • Someone, I think it was WiderMouthOpen, mentioned in another thread the possibility of upstream noise and the problems tracking down. I have now noticed that upstream power seems to go from ~46dB to 57dB when having problems. That is a more than a 10 fold increase in output power. That would seem to imply the head end is having noise/RX problems listening to customers. 

    Over the weekend I wrote a quick script to ping various devices and collect stats. I was away from home this afternoon, but the connection dropped repeatedly between 11:00am and 2:30pm today. A quick scan of the logs shows 30 drops in that time frame, between 1 and 20 seconds long each. Example drop:

    Date Time Router Modem CoxGW Google Server TX RX
    20211101 11:12:09 0.335ms 0.825ms 5.26ms 28.5ms 26.6ms 3Kbs 12Kbs
    20211101 11:12:10 0.298ms 0.702ms 7.15ms 25.6ms 24.8ms 3Kbs 8Kbs
    20211101 11:12:11 0.364ms 0.811ms 5.85ms 24.1ms 22.4ms 3Kbs 11Kbs
    20211101 11:12:12 0.326ms 0.850ms 5.84ms 26.1ms 26.3ms 3Kbs 12Kbs
    20211101 11:12:13 0.340ms 0.792ms 5.34ms 23.8ms 23.2ms 3Kbs 10Kbs
    20211101 11:12:14 0.332ms 0.805ms 6.46ms 25.7ms 23.8ms 4Kbs 19Kbs
    20211101 11:12:15 0.344ms 0.789ms ---ms ---ms ---ms 3Kbs 9Kbs
    20211101 11:12:16 0.246ms 0.797ms ---ms ---ms ---ms 3Kbs 8Kbs
    20211101 11:12:17 0.360ms 0.792ms ---ms ---ms ---ms 5Kbs 21Kbs
    20211101 11:12:18 0.349ms 0.766ms ---ms ---ms ---ms 3Kbs 7Kbs
    20211101 11:12:19 0.325ms 0.953ms ---ms ---ms ---ms 3Kbs 8Kbs
    20211101 11:12:20 0.339ms 0.803ms ---ms ---ms ---ms 3Kbs 7Kbs
    20211101 11:12:21 0.341ms 0.804ms ---ms ---ms ---ms 3Kbs 7Kbs
    20211101 11:12:22 0.269ms 0.780ms ---ms ---ms ---ms 3Kbs 8Kbs
    20211101 11:12:23 0.290ms 0.796ms ---ms ---ms ---ms 5Kbs 10Kbs
    20211101 11:12:24 0.248ms 0.800ms ---ms ---ms ---ms 7Kbs 12Kbs
    20211101 11:12:25 0.282ms 0.788ms ---ms ---ms ---ms 7Kbs 9Kbs
    20211101 11:12:26 0.259ms 0.849ms ---ms ---ms ---ms 5Kbs 7Kbs
    20211101 11:12:27 0.333ms 0.812ms ---ms ---ms ---ms 5Kbs 9Kbs
    20211101 11:12:28 0.337ms 0.788ms ---ms ---ms ---ms 3Kbs 8Kbs
    20211101 11:12:29 0.335ms 0.832ms ---ms ---ms ---ms 4Kbs 8Kbs
    20211101 11:12:30 0.336ms 0.810ms ---ms ---ms ---ms 3Kbs 8Kbs
    20211101 11:12:31 0.273ms 0.800ms ---ms ---ms ---ms 3Kbs 10Kbs
    20211101 11:12:32 0.333ms 0.826ms ---ms ---ms ---ms 6Kbs 13Kbs
    20211101 11:12:33 0.294ms 0.872ms ---ms ---ms ---ms 3Kbs 6Kbs
    20211101 11:12:34 0.346ms 0.838ms ---ms ---ms ---ms 5Kbs 14Kbs
    20211101 11:12:35 0.347ms 0.833ms 13.1ms 28.5ms 27.6ms 3Kbs 10Kbs
    20211101 11:12:36 0.315ms 0.770ms 5.77ms 24.1ms 21.7ms 31Kbs 42Kbs
    20211101 11:12:37 0.370ms 0.847ms 7.02ms 25.7ms 24.7ms 3Kbs 7Kbs
    20211101 11:12:38 0.330ms 0.647ms 5.51ms 24.0ms 22.2ms 3Kbs 15Kbs

    In this case I am simultaneously pinging 5 targets: my router, my Cox modem, the Cox gateway, Google 8.8.8, and my personal server in a Colo facility, plus collecting TX and RX rates in/out every second. Note I was not home, so the TX/RX are purely the ping script running and broadcast traffic received from the cable network. As can be seen above, all response beyond my modem stops, my TX rate remains constant, and my RX rate drops a few Kb/s (missing my ping responses, still seeing broadcast traffic).