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DPC3941T gateway reboots after receiving a phone call

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DPC3941T gateway reboots after receiving a phone call

I have had Xfinity TV, phone & internet service since 20 August 2019 and have noticed that my DPC3941T gateway often reboots after I receive a phone call.  During the 5 minute or so reboot process that occurs after the call ends, I am without phone and internet service.  An Xfinity technician came to my house on 24 September, but was not able to solve the problem.  Except for this rebooting problem, my TV, phone, and internet service work as expected.  Does anyone know how to solve this problem?  The solution offered in the "Modem restarts after receiving a call that leave a message" thread did not solve my problem.

Diamond Problem Solver

Re: DPC3941T gateway reboots after receiving a phone call

Is your phone plugged in directly to the modem or going through your home wiring?

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Re: DPC3941T gateway reboots after receiving a phone call


@CCAndrew wrote:
Is your phone plugged in directly to the modem or going through your home wiring?

My phone service goes through my home wiring and my home wiring includes an alarm system.  The rebooting does not seem to happen if I disconnect the home wiring and plug in a single phone into the modem.  Until I switched from Verizon to Xfinity in August, I did not have any phone problems.  The Xfinity installer disconnected my house phone wiring from Verizon and reconnected to the Xfinity modem.  Sorry I posted in the wrong community -- I am a new user.

Diamond Problem Solver

Re: DPC3941T gateway reboots after receiving a phone call

No worries, house phone wiring is hard to track down the cause. It takes time to eliminate the cause. Maybe check that your alarm is compatible and not causing issues. You could disconnect the alarm, hook the phone line back up going through the house wiring and see if the issue replicates

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Re: DPC3941T gateway reboots after receiving a phone call


@CCAndrew wrote:
No worries, house phone wiring is hard to track down the cause. It takes time to eliminate the cause. Maybe check that your alarm is compatible and not causing issues. You could disconnect the alarm, hook the phone line back up going through the house wiring and see if the issue replicates

Thanks!  My alarm system uses an RJ-31X connector to "sieze" the phone line ahead of all phones in the house.  I can try to disconnect at the RJ-31X.  Is there any way to find out what the modem doesn't like about my home wiring?  The modem log files are of no help and neither is the modem documentation.  If there is a house wiring problem, it doesn't stop the phone from working other than the reboots.  All phones have good dial tone, calls are loud and clear, and the modem can power all the ringers on my phones.  It would seem that the easiest solution would be to upgrade the modem firmware so that the modem doesn't reboot or to provide a way to control the conditions under which a reboot occurs.  It is unclear what useful purpose the rebooting servies and why Cisco programmed that behaviour into the modem.

Diamond Problem Solver

Re: DPC3941T gateway reboots after receiving a phone call

Usually if it’s rebooting, it’s acting like there’s a short somewhere. That’s the fun of troubleshooting phone wiring is eliminating everything one by one

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Re: DPC3941T gateway reboots after receiving a phone call


@CCAndrew wrote:
Usually if it’s rebooting, it’s acting like there’s a short somewhere. That’s the fun of troubleshooting phone wiring is eliminating everything one by one

Is there some kind of line tester that can be used to test for a short or other line fault?  That would seem to be more efficient than trial & error guessing.  Obviously, my wiring can't have much of a short, since the ringers ring and there is good call volume.  Also, the modem doesn't reboot on outgoing calls.  That might indicate the short is not continuous but time dependent or that there is a bug in the modem software.  Even if my house phone wiring isn't perfect, having a modem that reacts by rebooting doesn't seem to be a useful feature/behavior.