consistent lag issues

Hello, I've had xfinity for over 5 years at my current place and it's been uneventful until about a week or two ago when I noticed that on SSH connections, my cursor would freeze up for ~2-3 seconds at a time and then continue. This makes interactive remote work very difficult. I've narrowed the problem down somewhat. I don't think it's a problem with the local wifi network since I can run iperf and get consistent ~130mbs performance between 2 hosts connected to the same wifi network on their local addresses. However, the problem is evident when trying to reach a service on the outside web, like one of the iperf public servers:

➜ ~ iperf3 -t 20 -c ping.online.net -p 5201
Connecting to host ping.online.net, port 5201
[ 7] local 10.0.0.216 port 51212 connected to 51.158.1.21 port 5201
[ ID] Interval Transfer Bitrate
[ 7] 0.00-1.00 sec 640 KBytes 5.23 Mbits/sec
[ 7] 1.00-2.01 sec 1.38 MBytes 11.5 Mbits/sec
[ 7] 2.01-3.00 sec 896 KBytes 7.35 Mbits/sec
[ 7] 3.00-4.01 sec 1.12 MBytes 9.43 Mbits/sec
[ 7] 4.01-5.01 sec 1.00 MBytes 8.39 Mbits/sec
[ 7] 5.01-6.00 sec 768 KBytes 6.31 Mbits/sec
[ 7] 6.00-7.00 sec 384 KBytes 3.14 Mbits/sec
[ 7] 7.00-8.00 sec 256 KBytes 2.10 Mbits/sec
[ 7] 8.00-9.00 sec 512 KBytes 4.21 Mbits/sec
[ 7] 9.00-10.01 sec 384 KBytes 3.13 Mbits/sec
[ 7] 10.01-11.00 sec 384 KBytes 3.16 Mbits/sec
[ 7] 11.00-12.00 sec 512 KBytes 4.19 Mbits/sec
[ 7] 12.00-13.01 sec 128 KBytes 1.05 Mbits/sec
[ 7] 13.01-14.00 sec 0.00 Bytes 0.00 bits/sec <<<<<<<<<
[ 7] 14.00-15.00 sec 0.00 Bytes 0.00 bits/sec <<<<<<<<<
[ 7] 15.00-16.00 sec 0.00 Bytes 0.00 bits/sec <<<<<<<<<
[ 7] 16.00-17.01 sec 128 KBytes 1.05 Mbits/sec
[ 7] 17.01-18.01 sec 256 KBytes 2.10 Mbits/sec
[ 7] 18.01-19.01 sec 128 KBytes 1.05 Mbits/sec
[ 7] 19.01-20.01 sec 0.00 Bytes 0.00 bits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate
[ 7] 0.00-20.01 sec 8.75 MBytes 3.67 Mbits/sec sender
[ 7] 0.00-20.21 sec 8.71 MBytes 3.62 Mbits/sec receiver

You can clearly see one of those lag periods I observed over SSH.

Some other notes:
this happens with a VPN both enabled and disabled
this never used to happen, seems to start occurring about a month ago
i've brought the same machine that did the iperf test into my office and did the test there on ATT's network and there was no issue

I've tried restarting my gateway

Responses

Accepted Solution

BruceW

Gold Problem Solver

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26.3K Messages

8 days ago

... here's my gateway debug stats ...

Thank you. The downstream QAM power levels are borderline, and the OFDM power level is out of spec (all too low). Also, all of the upstream power levels are out of spec (too high). The error counts seem high, but it isn't possible to say for sure without know the uptime. All of these suggest a problem with the link between your XB6 gateway and Comcast's network

If you can't get the signals closer to the correct values, consider having a Comcast/Xfinity premise tech come out to identify and correct the problem as stated above.

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.

(edited)

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lollmao

Visitor

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8 Messages

9 days ago

➜  ~ sudo mtr 8.8.8.8 -tbzrwc50

Here is some additional debug info

Start: 2025-04-19T09:17:21-0700

HOST: xxx                                                               Loss%   Snt   Last   Avg  Best  Wrst StDev

  1. AS???    _gateway (10.0.0.1)                                                 0.0%    50    5.8   6.3   3.1  22.1   2.8

  2. AS???    100.92.141.195                                                      4.0%    50   39.8 356.3  20.4 3586. 801.0

  3. AS???    ???                                                                100.0    50    0.0   0.0   0.0   0.0   0.0

  4. AS7922   po-320-345-rur201.santaclara.ca.sfba.comcast.net (96.216.155.117)   6.0%    50  137.5 338.6  19.2 3403. 751.0

  5. AS7922   po-200-xar01.santaclara.ca.sfba.comcast.net (68.85.154.113)         2.0%    50   94.9 312.6  25.6 3312. 710.4

  6. AS7922   ae-242-rar01.santaclara.ca.sfba.comcast.net (96.108.99.249)         4.0%    50  114.4 324.0  34.3 3221. 683.3

  7. AS7922   be-299-ar01.santaclara.ca.sfba.comcast.net (68.86.143.93)          10.0%    50   29.6 392.0  18.1 4133. 890.4

  8. AS???    ???                                                                100.0    50    0.0   0.0   0.0   0.0   0.0

  9. AS15169  142.251.70.39                                                       4.0%    50   43.8 423.6  20.6 3951. 912.5

 10. AS15169  209.85.243.49                                                       2.0%    50   22.7 401.3  22.7 3860. 875.6

 11. AS15169  dns.google (8.8.8.8)                                                0.0%    50  232.4 409.2  20.1 3768. 832.5

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BruceW

Gold Problem Solver

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26.3K Messages

9 days ago

The enormous variation in RTTs to the first Comcast hop (a CGNAT IP BTW, best=20.4, worst=3586) suggests either a problem with a Wifi signal or a problem with the link between your modem or gateway and Comcast's network. Network connection problems that affect both Ethernet and Wifi devices 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 still need help, please post your Internet plan speed and the following information from your modem or gateway (from http://192.168.100.1 or http://10.0.0.1):

model number
uptime
downstream: power levels, SNR (or MER), and error counts for all channels
upstream: power levels for all channels
complete event log, if available (Be sure to remove or blot out any MAC addresses. Forum security processing considers them "personal information" and may prevent the event log from posting if these are present.)

Copy and pasted text is preferred over images. Be aware that, if you post any images, your message will be made Private for a time, as all images must be approved by the Forum Moderators before the messages containing them become generally visible.

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.

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lollmao

Visitor

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8 Messages

9 days ago

Thanks Bruce, I really appreciate the response.

I took a look at the coax cable connections and tightened one that had some play. Rerunning the trace route monitor, I'm getting better worst case RTT to the first Comcast hop, but also everyone in the house left for the day so if this is related to congestion due to the 5 tenants sharing the same gateway, then that could be hiding the issue.

For what it's worth, here's my gateway debug stats. I didn't find anything interesting in the event logs so I didn't include it.

Superfast Plan

Download speeds: up to 800 Mbps

Upgrade speed

Upload speeds: up to 150 Mbps

Cable Modem Info

HW Version: 13

Vendor: ARRIS Group, Inc.

BOOT Version: 0.2.15.573854

Core Version: kirkstone

Model: TG3482G

Product Type: XB6

Flash Part: 12980 MB

Download Version: 7.3.5.0.61

Downstream (DOCSIS 3.0 and 3.1)

Channel ID Lock Status Frequency (Hz) SNR (dB) Power Level (dBmV) Modulation

20 Locked 531000000 40.37 -8.20 QAM256

28 Locked 579000000 40.37 -7.10 QAM256

36 Locked 627000000 38.98 -9.40 QAM256

44 Locked 675000000 38.98 -8.00 QAM256

13 Locked 489000000 40.95 -7.40 QAM256

14 Locked 495000000 40.95 -8.00 QAM256

15 Locked 501000000 38.98 -8.20 QAM256

16 Locked 507000000 40.37 -8.20 QAM256

17 Locked 513000000 40.37 -8.50 QAM256

18 Locked 519000000 40.37 -8.50 QAM256

19 Locked 525000000 40.95 -8.50 QAM256

21 Locked 537000000 40.37 -8.00 QAM256

22 Locked 543000000 40.37 -7.70 QAM256

23 Locked 549000000 40.95 -7.30 QAM256

24 Locked 555000000 40.37 -7.30 QAM256

25 Locked 561000000 40.95 -7.10 QAM256

26 Locked 567000000 40.95 -6.90 QAM256

27 Locked 573000000 40.95 -7.00 QAM256

29 Locked 585000000 40.95 -7.20 QAM256

30 Locked 591000000 40.95 -7.20 QAM256

31 Locked 597000000 40.37 -7.40 QAM256

32 Locked 603000000 40.37 -7.90 QAM256

33 Locked 609000000 40.37 -8.00 QAM256

34 Locked 615000000 40.37 -8.70 QAM256

35 Locked 621000000 38.98 -9.10 QAM256

37 Locked 633000000 38.98 -9.80 QAM256

38 Locked 639000000 38.61 -9.80 QAM256

39 Locked 645000000 38.98 -9.70 QAM256

40 Locked 651000000 38.98 -9.20 QAM256

41 Locked 657000000 38.98 -9.00 QAM256

42 Locked 663000000 38.61 -8.30 QAM256

43 Locked 669000000 38.98 -8.50 QAM256

0 Locked 959800000 36.38 -14.70 OFDM

* Channel ID 20 is the Primary Channel.

Upstream (DOCSIS 3.0)

Channel ID Lock Status Frequency (Hz) Symbol Rate Power Level (dBmV) Modulation Channel Type

4 Locked 35600000 5120 KSym/sec 53.02 64QAM US_TYPE_ATDMA

1 Locked 16400000 5120 KSym/sec 53.27 64QAM US_TYPE_ATDMA

3 Locked 29200000 5120 KSym/sec 53.02 64QAM US_TYPE_ATDMA

2 Locked 22800000 5120 KSym/sec 53.02 64QAM US_TYPE_ATDMA

CM Error Codewords

Channel ID Unerrored Correctable Uncorrectable

20 34693363 19138 7694

28 34690215 18383 10242

36 1771694445 50695 20301

44 1731415757 1589529 17481597

13 1771659282 70711 40969

14 1771658798 63512 53781

15 7892832 0 0

16 7892911 0 0

17 1770621584 184380 337123

18 1771709010 57168 22276

19 1771723070 58643 24853

21 1771700493 60889 31570

22 1771718768 60951 31440

23 1771715369 63799 36545

24 1771722159 64239 34414

25 1771724728 64859 35720

26 1771722661 65802 41419

27 1771683784 65829 49511

29 1771739148 59773 36364

30 1771754372 59162 26931

31 1771758075 58686 28090

32 325857313 26898589 1896289

33 1771723854 79440 32713

34 1771792819 51879 18431

35 1771790572 50662 17314

37 1771782792 50389 16317

38 7895063 0 0

39 1664677099 67587843 40165257

40 1771820709 49412 15836

41 1771801860 52688 17803

42 1748015338 2200321 14464123

43 1753714144 1082352 9817520

Apologies for the formatting. The forum login only works on my phone browser (tried Safari, chrome, brave, private mode... on desktop but the sso pop-up hangs in every case)

(edited)

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lollmao

Visitor

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8 Messages

8 days ago

Some update is that I went through the coax cable path in my basement and found a section where the plastic jacket had been scraped off and the shielding thread was exposed. I wrapped it in electrical tape and rerouted the line so that I could lead more cable out upstairs and attach directly to the modem instead of through a splitter. This greatly reduced the RTT spikes down from consistent 500ms every 30 or so seconds to 100ms every few minutes. I can now connect persistently to the VPN that seems to have issues when there's any jitter in the network.

The power levels are still out of spec but since I can now use my company VPN it doesn't bother me so I'll call a tech if the issue reappears.

Thanks so much for the help

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lollmao

Visitor

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8 Messages

16 hours ago

Hello, my company uses globalprotect and it was working consistently until about 3 weeks ago when I'd get disconnected every minute.

The globalprotect client logs show this message when the issue occurs:

P1185-T31771 04/26/2025 07:09:14:014 Debug(7710): NetworkConnectionMonitorThread: Detected route change, but skip network discovery.
P1185-T259   04/26/2025 07:09:14:015 Debug( 356): receive sig 20
P1185-T19779 04/26/2025 07:11:10:485 Info (1354): --Too many outstanding keepalive and no response from GP gateway, disconnect tunnel
P1185-T19779 04/26/2025 07:11:10:486 Debug(1357): Tunnel downtime after keep-alive timeout is 54167 ms
P1185-T19779 04/26/2025 07:11:10:486 Info ( 631): VPN timeout due to keepalive, get out of ProcMonitor
P1185-T19779 04/26/2025 07:11:10:486 Debug( 647): In timeout handling, tunnel downtime is 54167 miliseconds
P1185-T19779 04/26/2025 07:11:10:486 Debug(6030): Show Gateway COMPANY_PORTAL_ADDRESS: Checking network availability and restoring VPN connection when network is available.
P1185-T19779 04/26/2025 07:11:10:486 Debug(8110): --Set state to Restoring VPN Connection

This will occur in a loop of connecting and reconnecting every minute and makes doing work impossible.

I have tried

improving the performance of my connection from the modem to the street
enabling bridge mode - I use a 3rd party router. Nothing has changed about this router in about a year
disabling the firewall
never enabled advanced security
connecting an ethernet cable to my laptop from the router and using a wired connection

Things that reliably works is to

Go into the office and use my company network (ATT)
Use my company's deprecated VPN portal. This is going away soon so I need a fix
downgrading my Mac's globalprotect client from 6.x to 5.x
using openconnect client on a linux machine on the home network

Given all these things, I'm pretty sure there's some interaction between the network and the VPN. I could use help so I can continue working from home.

Here's some examples of the dropped connections while connected to the VPN

Apr 26 07:10:16 64 bytes from 172.31.50.243: icmp_seq=101 ttl=63 time=33.731 ms
Apr 26 07:10:18 Request timeout for icmp_seq 102
...
Apr 26 07:11:26 Request timeout for icmp_seq 170
Apr 26 07:11:26 64 bytes from 172.31.50.243: icmp_seq=171 ttl=63 time=39.203 ms
...
Apr 26 07:12:34 64 bytes from 172.31.50.243: icmp_seq=239 ttl=63 time=47.117 ms
Apr 26 07:12:36 Request timeout for icmp_seq 240
...
Apr 26 07:13:47 Request timeout for icmp_seq 310
Apr 26 07:13:47 64 bytes from 172.31.50.243: icmp_seq=311 ttl=63 time=29.443 ms

While I'm not connected to the VPN, my pings are stable.

Arris TG3482G is my modem. Also I re-opened this thread after it was merged with an issue I previously posted about network jitter since this appears to be a different issue and I don't want this to be buried.

Note: This comment was created from a merged conversation originally titled Company VPN client disconnects every ~50 seconds

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Your Home Network

lollmao

consistent lag issues

BruceW

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.

lollmao

BruceW

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.

lollmao

lollmao

lollmao

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