M

Visitor

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3 Messages

Tuesday, February 15th, 2022 3:50 AM

Closed

Random DNS drops daily/Random Disconnects from the internet

For the past 4 months Ive been having daily DNS drops, sometimes multiple times a day. I thought it could be the modem so i contacted support and ended up getting a replacement modem. It was still happening, so i waited a  few days to see if it would stop, no luck so i contacted support again and they sent a technician out, They seen something wrong with the wire and completely redone the wire. The Online, US/DS and power lights are solid, 2.4 GHz and 5 GHz blink(This is also the lighting pattern when the DNS goes out) and it just keeps Looping Probing DNS and DNS connection error until I Unplug it for 20 minutes and replug it, then it just does the same thing the next day. I was talking with the technician trying to find out if it truly was just a Wire/Modem/Connection problem. But they didnt really say any other causes of the issue so i figured it would be fine. What other issues could cause it and what could be a solution?

I tried contacting support again today, but nothing came out of it other than "Senior Technician visit". which i refused because I dont think it would actually help. They didnt seem to realize that its not an issue i was having at the moment of contacting them, but a chronic issue that i would love to find a fix for because my brother lives quite litterally, 60 feet away from me, He has his own comcast modem and bill and he doesnt get any of the DNS issues i do.

Just to add another bit of info: I have 2 devices, a PC on ethernet and Wifi on a phone, Both things get no connect when the issue occurs

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Expert

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106.9K Messages

3 years ago

Many times general connectivity problems manifest themselves as being DNS issues when they really aren't. That said. 

Start with the modem's signal stats. Perhaps they already are, or they are close to being out of spec and intermittently they go completely of spec. Try getting them here http://192.168.100.1 or here http://10.0.0.1 


Please copy all of the text in its entirety of the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers and paste them into your next post.


What is the exact make and model number of the modem ?

(edited)

Visitor

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3 Messages

3 years ago

Cable Modem

HW Version:1.0
Vendor:Cisco
BOOT Version:3.4.19.1
Core Version:3.12.14
Model:DPC3941T
Product Type:XB3
Flash Part:128 MB
Download Version:2.3.10.13_5.5.0.5
Serial Number:273898615
Downstream
Channel Bonding Value
Index
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Lock Status
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency:
381 MHz
303 MHz
309 MHz
315 MHz
321 MHz
327 MHz
333 MHz
339 MHz
345 MHz
357 MHz
363 MHz
369 MHz
375 MHz
387 MHz
393 MHz
399 MHz
405 MHz
411 MHz
417 MHz
423 MHz
429 MHz
435 MHz
441 MHz
453 MHz
SNR
38.983 dB
38.983 dB
40.366 dB
40.366 dB
40.366 dB
40.366 dB
38.983 dB
38.605 dB
38.983 dB
38.983 dB
38.605 dB
38.983 dB
38.983 dB
38.605 dB
38.983 dB
38.983 dB
38.983 dB
38.983 dB
38.983 dB
38.983 dB
38.983 dB
38.983 dB
38.605 dB
38.605 dB
Power Level
3.300 dBmV
4.100 dBmV
4.200 dBmV
4.500 dBmV
4.600 dBmV
4.700 dBmV
4.500 dBmV
4.300 dBmV
4.000 dBmV
2.900 dBmV
2.400 dBmV
2.400 dBmV
2.600 dBmV
3.800 dBmV
3.800 dBmV
3.800 dBmV
3.800 dBmV
3.700 dBmV
3.600 dBmV
3.400 dBmV
3.300 dBmV
3.400 dBmV
3.300 dBmV
3.300 dBmV
Modulation
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
Upstream
Channel Bonding Value
Index
1
2
3
4
Lock Status
Locked
Locked
Locked
Locked
Frequency:
23 MHz
36 MHz
30 MHz
17 MHz
Symbol Rate
5120 KSym/sec
5120 KSym/sec
5120 KSym/sec
5120 KSym/sec
Power Level
36.500 dBmV
36.500 dBmV
36.500 dBmV
35.750 dBmV
Modulation
64 QAM
64 QAM
64 QAM
64 QAM
Channel Type
ATDMA
ATDMA
ATDMA
ATDMA

This is what it is like when its operating as it should be, Ill update this post the next time it cuts out and gives me the error again. Its only been happening once a day and it hasnt hit yet today

Expert

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106.9K Messages

3 years ago

The signal stats looked good / in spec at that snapshot in time. 

Visitor

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3 Messages

3 years ago

Alright it just happened again aand i couldnt connect to 10.0.0.1 to check the stats

also the error i get ERR_NAME_NOT_RESOLVED then it would try to refresh the "name" until i unplug and leave it off for a while

Official Employee

 • 

6.9K Messages

Hello @Millingway! Thank you for posting and sharing your experience here on the Xfinity Community Forum. I'd be more than happy to investigate this further. Can you send a direct message with your first and last name and service address? To send a direct message click the "Direct Messaging" chat icon in the top right corner of the page, then click on the pen and pad icon and enter "Xfinity Support" in the "To" section of the chat.

I no longer work for Comcast.

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

Expert

 • 

106.9K Messages

3 years ago

Even though the signal stats looked o/k at that snapshot in time,  perhaps there is noise ingress into the line(s) / an upstream channel-return path impairment somewhere.


There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.


I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

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