U

Thursday, October 31st, 2024 5:37 PM

Disconnects and now slow connection

I am writing about a problem with my PC connected to internet by ethernet.  I have an Amplifi Alien Router and a Nighthawk CM2000 modem purchased from Xfinity.  There are no splitters in the cable leading to my home or inside my home.  It only connects to the one modem.  I have been using this set up for nearly a year without any trouble. 

About ten days ago, my internet started randomly disconnecting every 5-10 minutes.  I first noticed it while gaming (getting kicked off game), but I have determined it also impacts web browsing.  The modem app says "A network change was detected" when this happens. 

About 2 days ago, while attempting to work on the issue the modem now reads Cable Connection status as "poor" at all times, and my speed test is under 100 mbs (I have the highest level plan 1.2 GB I believe).  Before I was getting up to 800 mbs.

I have tried many many things.  I have reset and restarted the modem, router and PC dozens of times.  I have plugged modem directly into PC without any change.  When I use the xfinity assistant, it says my connection and modem are good.

My cable connection report looks like this except the downstream status is yellow (not sure why it is green in copy and paste:

Cable Connection
Cancel Apply
Cable Diagnostic
Status:   Poor
Action:  
[Partial Service]
If the Partial Service mode does not go away within a few hours (Click the Refresh button after each step):
1) Make sure the coaxial cable is tightly connected.
2) Remove any unnecessary splitters.
3) Replace any required ones.
4) Contact your service provider for troubleshooting help.
[Downstream SNR]
Try these actions (Click the Refresh button after each step):
1) Make sure the coaxial cable is tightly connected.
2) Remove any unnecessary splitters.
3) Replace any required splitters.
4) Contact your service provider for troubleshooting help.
CM Status: 
Downstream Status: 
Upstream Status: 
  Refresh Save Cable Diagnostic Info
 
Advanced Information
Frequency Start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
 
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 591000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
Downstream Bonded Channels (Partial Service)
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 28 591000000 Hz -0.9 dBmV 35.9 dB 0 0
2 Locked QAM256 1 429000000 Hz 0.2 dBmV 44.6 dB 0 0
3 Locked QAM256 2 435000000 Hz -0.1 dBmV 44.3 dB 0 0
4 Locked QAM256 3 441000000 Hz -0.3 dBmV 44.2 dB 0 0
5 Locked QAM256 4 447000000 Hz 0.2 dBmV 44.3 dB 0 0
6 Locked QAM256 5 453000000 Hz -0.1 dBmV 43.9 dB 0 0
7 Locked QAM256 6 459000000 Hz -0.2 dBmV 44.1 dB 0 0
8 Locked QAM256 7 465000000 Hz 0.3 dBmV 44.1 dB 0 0
9 Locked QAM256 8 471000000 Hz 0.1 dBmV 44.2 dB 0 0
10 Locked QAM256 9 477000000 Hz -0.1 dBmV 44.0 dB 0 0
11 Locked QAM256 10 483000000 Hz 0.1 dBmV 44.2 dB 0 0
12 Locked QAM256 11 489000000 Hz 0.2 dBmV 29.3 dB 43 0
13 Locked QAM256 12 495000000 Hz -0.4 dBmV 33.2 dB 0 0
14 Locked QAM256 13 501000000 Hz -0.2 dBmV 31.6 dB 0 0
15 Locked QAM256 14 507000000 Hz -0.2 dBmV 30.4 dB 0 0
16 Locked QAM256 15 513000000 Hz -0.8 dBmV 37.4 dB 0 0
17 Locked QAM256 16 519000000 Hz -0.5 dBmV 43.9 dB 0 0
18 Locked QAM256 17 525000000 Hz -0.4 dBmV 43.9 dB 0 0
19 Locked QAM256 18 531000000 Hz -0.8 dBmV 27.7 dB 32500 14
20 Locked QAM256 19 537000000 Hz -0.5 dBmV 26.4 dB 9653402 1414263
21 Locked QAM256 20 543000000 Hz -0.3 dBmV 33.0 dB 0 0
22 Locked QAM256 21 549000000 Hz -0.9 dBmV 43.5 dB 0 0
23 Locked QAM256 22 555000000 Hz -1.0 dBmV 43.4 dB 0 0
24 Locked QAM256 23 561000000 Hz -0.7 dBmV 43.6 dB 0 0
25 Locked QAM256 24 567000000 Hz -0.8 dBmV 43.4 dB 0 0
26 Locked QAM256 25 573000000 Hz -0.9 dBmV 43.3 dB 0 0
27 Locked QAM256 26 579000000 Hz -0.3 dBmV 43.7 dB 0 0
28 Locked QAM256 27 585000000 Hz -0.8 dBmV 43.4 dB 0 0
29 Locked QAM256 29 597000000 Hz -0.1 dBmV 42.1 dB 0 0
30 Locked QAM256 30 603000000 Hz -0.6 dBmV 43.4 dB 0 0
31 Locked QAM256 31 609000000 Hz -0.5 dBmV 43.4 dB 0 0
32 Locked QAM256 32 615000000 Hz -0.1 dBmV 43.5 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 19 5120 Ksym/sec 29200000 Hz 50.8 dBmV
2 Locked ATDMA 18 5120 Ksym/sec 22800000 Hz 50.0 dBmV
3 Locked ATDMA 17 5120 Ksym/sec 16400000 Hz 49.3 dBmV
4 Locked ATDMA 20 5120 Ksym/sec 35600000 Hz 50.8 dBmV
5 Not Locked Unknown 0 0 0 0.0 dBmV
6 Not Locked Unknown 0 0 0 0.0 dBmV
7 Not Locked Unknown 0 0 0 0.0 dBmV
8 Not Locked Unknown 0 0 0 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock Status Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 193 957000000 Hz -3.52 dBmV 39.4 dB 148 ~ 3947 3945465 3910410 584
2 Not Locked 0 0 0 Hz 0 dBmV 0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV
 
Extended Upstream Transmit Power
 
Current System Time:Thu Oct 31 12:15:55 2024
System Up Time:00:10:51

From my tests and removal of the router, I can only conclude that I have a problem with the modem or connection to the modem.  I have used different ethernet cables with no relief.  Any thoughts would be welcome, even if it is "you need to have a service visit."

Gold Problem Solver

 • 

26K Messages

8 days ago

Several downstream channels have out of spec SNR values (too low), and all the upstream channels have borderline power levels (too high). Network connection problems like this are often due to poor coax connections or damaged coax cable, usually in or near your home. Running the cable through a surge protector, a defective splitter, or too many splitters can cause signal problems as well. If there is an amplifier in the line make sure it's getting power. 

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you can't find the problem or you'd rather have Comcast take care of it and an employee does not respond to your message here, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit (approx $100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Official Employee

 • 

1.4K Messages

7 days ago

Hi there user_wslq80! Thank you so much for reaching out regarding your service issues you are having recently with your Internet service. You are in the right place and we are happy to take a look at your connection remotely and see if we can get it fixed. 

Please send us a direct chat message with your full name and complete service address to “Xfinity Support”. To do so, click on the chat icon located at the top right of this forums page.

Here's the detailed steps to direct message us:

  • Click "Sign In" if necessary
  • Click the "Direct Message” icon (upper right corner of this page)
  • Click the "New message" (pencil and paper) icon
  • Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
  • Type your message in the text area near the bottom of the window
  • Press Enter to send your message

 

Let me know if you have any questions.

 

3 Messages

service visit in the morning.  We will see.

Official Employee

 • 

2.7K Messages

@user_wslq80 Thank you for letting us know that you have a technician coming this morning. Please let us know how you make out and if you need further assistance. We will also set a reminder to follow up, in case we haven't heard from you. It's important to us that your service issues be 100% resolved.

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3 Messages

Service tech recommended new modem (just bought 3.0 modem on recommended list less than a year ago), so I did that.  Did not stop disconnects.  Been in chat for 2 days with Xfinity with many promises of addressing local issues.  Did not stop disconnects.  I guess next I try new router and new ethernet card for PC.  Just pouring money into an issue without any resolution.  Although my internet has gotten faster, if anything the disconnects are more frequent.  Going on about 3 weeks now.  I even had a critical event this afternoon when I was not even home: 

Thu Nov 07 17:20:58 2024 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Upstream and downstream power numbers seem OK.  Is it normal to have upstream bonded channels 5-8 be "not locked?"

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