High first hop latency - Modem Connection stats or somewhere between?

[Justin_B]

For several months I have occasional issues where I experience some combination of extremely variable latency to the first hop, or large amounts of packet loss. However, the problem seems to have been exacerbated by people being forced to work from home recently, with the problem extremely bad during the day, and worse in the evening than it used to be.

I used to be using a Motorola Surfboard SB6121, and contacted comcast. They suggested that I contact the modem manufacturer. I decided against this and just purchased a Netgear CM1000. I've been running this for a few weeks now, and the issue is still apparent, with no change.  I've only now started keeping track of actual data.

I'm hard wired to my switch (An EdgeRouterX), and my SO is connected via wifi from a Netgear router acting as an AP. Both machines see the same issues. I've also swapped out the EdgeRouter for an old Belkin router that I know was working a year ago, and the issues were still present.

Two additional contacts with CS have just had them restart my modem, without it doing anything other than taking down my internet for a minute.

First hop is 96.120.101.197. I'm located in WA, for context regarding ping times.

from Digital Ocean NY2
--- 96.120.101.197 ping statistics ---
31 packets transmitted, 31 received, 0% packet loss, time 30051ms
rtt min/avg/max/mdev = 81.408/81.518/81.724/0.397 ms

from internal network
--- 96.120.101.197 ping statistics ---
31 packets transmitted, 29 received, 6% packet loss, time 30072ms
rtt min/avg/max/mdev = 12.566/44.701/140.133/38.087 ms

from internal network to modem
--- 192.168.100.1 ping statistics ---
31 packets transmitted, 31 received, 0% packet loss, time 30061ms
rtt min/avg/max/mdev = 0.970/1.509/1.889/0.199 ms

No apparent internal network issues.

More data:

Modem 

Modem page

More modem 

more modem

Late at night 

Late at night

Technician attempted to fix the issue by restarting my modem 

Technician attempted to fix the issue by restarting my modem

midday jitter is ridiculous 

midday jitter is ridiculous

[BruceW]

The images you posted aren't visible. They all look like this:

This is probably because the images require moderator approval. That could take a while. You could upload the images to a file sharing site and post links to them here, or post text instead of an image.

[Justin_B]

modified the post to include imgur links for now

[BruceW]

The downstream power levels are on the low side but still in spec, but the upstream power levels are borderline/out of spec (too high). This is often due to poor coax connections or damaged cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Connection Troubleshooting Tips. If you can't find the problem call Comcast 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/. If they can't fix the problem remotely (that's unlikely), 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 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.

[Justin_B]

Both times I've contacted they've mentioned they're only sending techs to people who do not have a connection working. Mine works, it's just bad sometimes.

I realized the upstream was barely out of spec, but I'm skeptical if this is the cause. Wouldn't I have a much larger uncorrectable codewords if that was the case? I also feel like the issue would not be dependent on time-of-day.

[BruceW]

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@Justin_B wrote: ... I realized the upstream was barely out of spec, but I'm skeptical if this is the cause. Wouldn't I have a much larger uncorrectable codewords if that was the case? ...

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The correctable/uncorrectable codeword counts the modem reports are only for the downstream channels, not the upstream.

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... I also feel like the issue would not be dependent on time-of-day.

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Variations in temperature, moisture, mechanical vibration, and other factors can cause the RF characteristics of a poor connection to change, resulting in varying signal levels and varying signal quality.

[Justin_B]

Well, the other thing is that when I first moved here, the issue was not present either.  I do know that some road construction took place somewhat nearby. I can't remember though if the issues occured at the same time though.

[BruceW]

I obviously do not know what the cause of the problem you are seeing is.

It may not be near you, and it may not be a coax connection problem. But that's what's most common, and that's where Comcast would start looking if they were to come out to troubleshoot. And it's the only part of an Internet connection that users can inspect and perhaps repair themselves.

If a service tech were to determine that signal impairments exist where Comcast's network connects to your drop, they're supposed to refer it to a line tech to check further upstream, all the way back to the headend and beyond, if necessary.

If you are able to solve this, or if it gets worse, please post to let us know!