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DPC3941T drops internet when phone rings

Frequent Visitor

DPC3941T drops internet when phone rings

Since installing new DPC3941T gateway in late February 2018, have had intermittent internet interruptions of 4 to 5 minutes.  I have X1 Triple Play service.  Phone line is plugged directly into gateway.  Finally noticed that the internet interruption occurs immediately after the phone rings, but not every time the phone rings.  Most often when I get a call from a number I don't recognize and don't answer, i.e., marketing or robocalls.  Coincidence or not?  Nevertheless, the internet goes down for 4 to 5 minutes.  I do not use a separate router.

After reading other problems on this forum with internet drops with the DPC3941T, some seemed to be related to earlier devices that were defective in 2017.  But I would have hoped that Comcast would not still be sending out old defective equipment a year later.  Also some folks had problems that may have been complicated by the use of a separate router or other issues.  Mine is pretty straightforward.  I use the gateway for the phone, router, wifi, everything, so there's no complicated setup or other equipment involved.   I haven't called Comcast yet about this issue but thought I'd see if anyone else has noticed their internet interruptions associated with incoming phone calls.


Accepted Solutions
Frequent Visitor

Re: DPC3941T drops internet when phone rings

Thanks for following up ComcastElla.  Since the technician came out and replaced the gateway with another DPC3941T on April 27, 2018, there have been no further internet interruptions when the phone rings, and no new issues have cropped up.  Everything is working fine.   Thanks so much for your help.  Someone's early reply to my original post suggested it was a hardware issue--he/she was right! 


All Replies
Expert

Re: DPC3941T drops internet when phone rings

Based on my experience, a device exhibiting that behavior needs to be replaced. Smiley Sad

 

I've asked a Comcast employee to help you. You should expect a reply in this thread. 

Silver Problem Solver

Re: DPC3941T drops internet when phone rings

Just a thought, are you using a cordless phone system? Does your wired internet cut out or is it just wireless? If just wireless try logging into the gateway to change the wireless channel from auto to manual on the 2.4 network, try channel 1, 6 or 11. If your phone operates on 2.4 Ghz could be just interference

 

Official Employee

Re: DPC3941T drops internet when phone rings

Hi, NewNameCC - I can check your gateway, please private message me your full name, the account holder's name and address as it listed on the billing statement, a phone or an account number. Click on my name ComcastElla, then click Private Message Me.  

New Poster

Re: DPC3941T drops internet when phone rings

comcastella,  we have the same problem with the internet dropping for about 5 minutes or so every time the phone rings from a robocall.  It appears real people we know can call us and the internet stays up, since we have been able to use it while talking on the phone.  Can you help us with this?

Tags (3)
Frequent Visitor

Re: DPC3941T drops internet when phone rings

To dandbthompson - I sent a private message to ComcastElla yesterday with my account info as she requested.  She checked out the gateway and everything looks okay, but before replacing the unit she was waiting to speak with a collegue who is a phone expert.  I'm still waiting to hear back.   I think I have isolated the problem to telemarketing robocalls.  If the gateway could filter out those annoying calls WITHOUT interrupting internet connectivity, that would be awesome.  I also am able to receive nomal calls from real people with whom I speak without the internet interruption.  I just tried an experiment by calling my landline from my cell phone, but didn't answer the landline as I don't answer robocalls, and there was NO internet interruption.  So, I'm hoping the phone guru can figure out how the robocalls cause such a disruption when "real" calls don't.  Stay tuned...

Official Employee

Re: DPC3941T drops internet when phone rings

Hello all,

 

@NewNameCC - I did talk to my phone guru Smiley Happy Since you originally stated that the internet connection drops every time when somebody calls, he stated that it can only be an issue with the gateway but it rarely happens. However, if the internet connection drops only when you receive robocalls, I have a question for you. Have you tried a Nomorobo feature? I emailed you the steps to set it up. 

 

@dandbthompson - I emailed you the steps as well. 

 

Please let me know how it goes. 

Frequent Visitor

Re: DPC3941T drops internet when phone rings

ComcastElla, thanks for your reply.  I have not set up Nomorobo yet, but will think about that OR just discontinue my phone service altogether.  As I understand it, with Nomorobo, the phone will ring through once before it's diverted, so I question whether or not that will solve the internet disruption problem.  Additionally, the Nomorobo will not stop charity calls.  So, I need to pay closer attention to the source of the calls that cause the internet disruption before deciding how to proceed.  I have been keeping a log of the times of incoming calls with internet disruption, but have not logged the source of the call in an attempt to distinguish those which are automatic phone dialers with real people on the other end when I answer which would normally be a charity soliciting donation or whether they are auto dialers with a recorded message such as a politician seeking my vote or a weather emergency notification from the local municipality.  I'm not sure which of those is technically a "robocall".   I'll get back with you after gathering more information.  Thanks.

Silver Problem Solver

Re: DPC3941T drops internet when phone rings

Sorry, but whatever the problem is doubt it's to do with robocalls.

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Paranoid, why do you think the problem is not associated with robocalls?  There's an obvious connection between some type of phone calls and the internet disruption.  I can't quite isolate exactly what type of calls, but have been tracking them for 2 days and don't have enough data to draw a conclusion yet, but so far here's what I know.  First of all, my phone system allows me to block callers, which I have done for some of the regular annoying calls, but the perpetrators change numbers so quickly, that doesn't always work.  Anyway, here's what's happened so far:

1.  Charity caller, I answered & internet went down - don't know if the caller manually dialed my or if it was an auto dialer, but there was a live person on the other end when I answered the call on the 2nd ring.

2.  Call from unknown number (caller ID showed a series of 14 digits), I answered & internet went down - when I picked up the line on the 2nd ring, I did not speak and nobody was on the other end, which I suspect was a recorded message set to start only if it detected a live voice answer--this I would definitely define as a robocall.

3.  Call from charity which I had blocked on my phone system, so it rang once, then stopped and internet did NOT go down. Nomorobo would not help in this case since it doesn't screen charities.

4.  Call from recognized person who manually dialed my number and we talked - internet did NOT go down.

I'm going to continue to log all calls and answer some of the unrecognized numbers to see whether or not there's a recording or live person calling. So far, my thinking is that computer controled auto dialed calls are causing the problem, whether or not it's a live person once the connection is made or whether it's a recorded message, but will keep investigating and get back with you when I have more data.  I'm obsessed with this, but if I can't figure it out, then will either swap the gateway or discontinue landline service with Comcast.

 

Silver Problem Solver

Re: DPC3941T drops internet when phone rings

I think it's far more likely that it's wireless interference from a cordless phone set. You never did answer my question if your wired devices were cutting out too. Wireless interference can by stopped as I explained in my earlier post.

If your wired internet does cut out then it's likely a signal problem. (or faulty gateway)

Take a look at the troubleshooting here:

https://forums.xfinity.com/t5/Your-Home-Network/Xfinity-Internet-Connection-Troubleshooting-Tips/td-...

 

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Paranoid, sorry I didn't respond fully to your previous question.  My desktop computer is plugged into the gateway by ethernet cable and yes, this wired device does lose connectivity to the internet when certain calls come in.  I looked at the troubleshooting tips you suggested and it all seems a bit intimidating to me.  I didn't think further analysis was needed since ComcastElla checked on my gateway status when she replied in a private message that "I checked your modem settings, RF signal levels, phone provisioning and didn't find any issues."  Tomorrow I'll work on unplugging, rebooting and get the vital statistics readings for you or someone to interpret for me, if I can. 

 

My rant for the day:  With all the money I pay Comcast, I would hope they could afford technical support that could figure this stuff out without me (and other customers) having to spend endless hours of frustration trying to troubleshoot their equipment or system issues.  Arggg...  All I want is to be able to adequately explain the symptoms so the "doctor" can provide an accurate diagnosis and treatment. 

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Good morning, Paranoid,

I powered down the DPC3941T this morning and checked the Gateway stats, although I'm not sure what's important to see.  I cannot see the signal strength information mentioned in the troubleshooting tips article you referred me to--let me know if I'm just not looking in the right place.  I logged in to the 10.0.0.1 and looked at everything I could find, but still no signal strength info.  However, here's the event log for Friday when I experienced 2 internet disruptions after incoming phone calls.  The time stamps on these events (assuming the 24 hour clock in my ET zone) do not coincide with the times of the internet disruptions.  Let me know if any other information would be helpful to you in analyzing the problem.

[Dhcpc][2217]: erouter0 got new IP 24.30.95.172 2018/4/20 20:41:07 Notice
[Dhcpc][2045]: mta0 got new IP 21.02.149.00 2018/4/20 20:40:54 Notice
[Dhcpc][2115]: erouter0 got new IP 24.30.95.172 2018/4/20 19:19:20 Notice
[Dhcpc][1928]: mta0 got new IP 21.02.149.00 2018/4/20 19:19:10 Notice
[Docsis][945]: No Ranging Response received - T3 time-out 2018/4/20 00:42:16 Critical
[Docsis][945]: No Ranging Response received - T3 time-out 2018/4/20 00:42:14 Critical
[Dhcpc][2136]: erouter0 got new IP 24.30.95.172 2018/4/20 00:34:30 Notice
[Dhcpc][2028]: mta0 got new IP 21.02.149.00 2018/4/20 00:34:24 Notice

 

The good news is that I received 2 bona-fide political robocalls last night and this morning, which I did answer and it did not interrupt the internet connection.  So, maybe it's only the ones I don't answer that cause the problem.  Still searching for answers...Thanks for your help.

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Just did a speed test, can someone help me interpet the results, please and if this has any affect on the internet disruption when the phone rings:

Download speed 113.41 Mbps

Upload speed 11.73 Mbps

Silver Problem Solver

Re: DPC3941T drops internet when phone rings

Well the speed is ok if you are paying for Blast! 100/10.

The signals you need to post are the downstream power levels and SNR and the upstream power levels.

With the gateway you would have to scroll horizontally to see all your downstream channels.

They may or may not show a problem, could be something intermittent seeing as Comcast Ella already took a look.

Regular Visitor

Re: DPC3941T drops internet when phone rings

I have the problem of my phone ringing and it disconnects my internet and phone. I have reported this time after time and no help. It happens at least once a day and often happens when an unknown call comes in but can happen anytime...It takes about 5 minutes to reboot. I have a wireless 6.0 phone tied directly into the modem/router but I have had this set up for almost 7 years with previous modem/routers and this problem started over a year ago and has gotten worse especially with the Technicolor Model DPC 3941T modem/router that I rent from Comcast. I am tired of being on the phone to so-called Comcast support people I can't understand and who don't know what they are doing.  Any suggestions that will work?

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Paranoid, Please tell me where to find the downstream & upstream power levels and SNR of which you speak.  Point me to the correct menu selection on my Gateway.  Here are the menu options I see, but can't find any power levels or SNR's anywhere.  Thank you for your help and patience.

 

Expert

Re: DPC3941T drops internet when phone rings

Have you looked under "Connection" >> "Status" ?

Frequent Visitor

Re: DPC3941T drops internet when phone rings

EG, I did look at connection status, but there's nothing there about downstream or upstream power levels or SNR that Paranoid suggested I post.  The connection status screen has 5 boxes with blue headers: 1) Local IP Network, (2) Xfinity network, (3) MoCA, (4) Private WiFi Network (2.4 Ghz), and (5) Private WiFi Network (5.0 Ghz).  Within each of those 5 boxes there's some information, mostly MAC addresses, DNS server info, and such, but nothing about power levels or SNR.  Any other suggestions?

Official Employee

Re: DPC3941T drops internet when phone rings

Hello all,

 

@NewNameCC - I understand your frustration. For me, as a person who came from Tier 3 Technical Support team for Internet/Cable issues, your issue sounds like a faulty gateway. I haven't found any issues on the signal side but please feel free to click on Connection -> XFINITY Network -> Scroll down and you will see Downstream and Upstream Channel Bonding Value. At the same time, I can ship you a new modem (different model). 

 

@acethedog - I can check your gateway. Seems like this issue could be related to one specific gateway model - DPC3941T. Please send me a private message and include your full name, the account holder's name and address as it listed on the billing statement, a phone or an account number. 

 

@Paraniod and @EG - I appreciate your help, thank you so much!

Expert

Re: DPC3941T drops internet when phone rings

No prob Ella ! It's what we do here !
Frequent Visitor

Re: DPC3941T drops internet when phone rings

Comcast tier 3 technician arranged by ComcastElla just left after replacing gateway with same model.  He checked all the lines and connections outside the house and everything looked fine there.  He came inside and made a test call to the landline and, lo and behold, the gateway shut down 30 seconds later, so he got to observe the behavior I've been experiencing for months.  After checking everything he could inside, he concluded it had to be a hardware problem and replaced the gateway.  So, time will tell whether this is a good one or not.  I'll report back after a week or so.  Thanks so much to ComcastElla for arranging the technician and for her diligence in following through.  Stay tuned for what I hope will be a report of "problem resolved" in a week or two. 

Official Employee

Re: DPC3941T drops internet when phone rings

@NewNameCC - Thank you so much for letting us know. I hope the issue has been resolved but I will follow up in a week. 

Official Employee

Re: DPC3941T drops internet when phone rings

@NewNameCC - How is the service? Have you noticed any issues? 

Regular Visitor

Re: DPC3941T drops internet when phone rings

Still having issues..not as many. Tech suppose to come tomorrow afternoon between 3 and 5 pm

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Thanks for following up ComcastElla.  Since the technician came out and replaced the gateway with another DPC3941T on April 27, 2018, there have been no further internet interruptions when the phone rings, and no new issues have cropped up.  Everything is working fine.   Thanks so much for your help.  Someone's early reply to my original post suggested it was a hardware issue--he/she was right! 

Frequent Visitor

Re: DPC3941T drops internet when phone rings

Thank you, Nerdberg, you were right about it being a hardware failure.  Replacement of the gateway with another of the same model DPC3941T solved the problem of internet interruptions when the phone rings. 


@nerdburg wrote:

Based on my experience, a device exhibiting that behavior needs to be replaced. Smiley Sad

 

I've asked a Comcast employee to help you. You should expect a reply in this thread. 


 

Official Employee

Re: DPC3941T drops internet when phone rings

@acethedog - Just sent you an update regarding your issue. Please check your inbox. 

 

@NewNameCC - I'm very happy to hear that the issue is finally resolved! Please feel free to reach me at any time.