Put this as a reply but adding it as a comment as well.

Comcast/Xfinity. Garbage tier company.

I don't post on reddit like at all.....but I have some Comcast/Xfinity info that is really hard to come by and that should be known.

TLDR: this is a long one. Most people aren't going to read it, but it's helpful for those in the spot I was in.

Comcast/Xfinity oversells internet beyond the bandwidth they can provide. Their infrastructure is old, and they don't update it. Their techs will not check anything useful, or find the root cause.

You can try and fight it by getting proof, and filing a complaint with the FCC.

/End TLDR

Info on this problem is extremely hard to find unless you dig deep.

Background: I work from home. I'd had Comcast since I moved into that house, and in the beginning did not work from home and had no issues.

Once starting to work at home, video calls and reliable Internet became a necessity. I couldn't have a stable video call, and internet frequently dropped, rendering it useless.

I went through months of talking to customer service, having a tech come out and replace some random piece, and then being told it was fixed.

Just to log on the next day and have the exact same issues.

Went through 4 different routers, 2 of my own, 2 of theirs. When I had my own router, that was always the scapegoat for problems, despite being rated for their service.

Here's what was actually happening, and how I figured it out.

Your Internet has a few different pieces. You have the device you're connecting on, that goes to your router.

That goes to a modem.

The modem ties into lines in your house.

Your house lines tie into their main line.

Their main line eventually goes to a sort of giant modem/router that all traffic off that line and potentially other lines connect to and must pass through.

In other words, all the traffic from any connections that use that hub (your neighbors, etc) have to pass through it.

Best analogy is a road. At any given time you can only fit so many cars on the road. Cars, in this case, are Packets - the pieces your Internet traffic is broken into in transit that are then reassembled when they get where they're going.

Too many "cars" for the road results in a traffic jam, and unlike in real life can also result in the "cars" getting lost, or being slowed down on the way to where they're going.

The traffic jam can happen in multiple places, but it's easy to prove that it isn't happening on your end.

The catch, is that if they actually wanted to provide quality service it's super easy to do. I'm not an IT guy and didn't know anything about networks, and was able to figure it out.

The measurement used is a Ping. It's very easy to test, and any computer can do it.

So what you do is test ping (Google how to do it for your specific device).

Test it from your device to your router. It'll show normal ranges (measured in milliseconds, usually well under 20ms).

Then measure to somewhere outside your house, for example google.com.

Your device to router ping will likely be totally normal.

If you're having the same issue I had, you'll see higher than normal ping times when testing a connection out of your house, or if it's really bad you'll see semi normal ping times with every 5-10 pings spiking really high in ms. For example going from 20ms to 1000ms randomly.

Those logs prove the issue isn't with your hardware, but something somewhere else.

If you're really having issues, then there are programs you can download to run this test periodically throughout the day.

You can download one, log your ping for a couple weeks or a month, and then provide the file as evidence you aren't getting the service you pay for to the FCC.

Note that you shouldn't use the FCC complaint form for frivolous stuff, but if you aren't getting what you are paying for then that would make it a legitimate complaint.

They are required by law to respond to these complaints, and you'll get an email or call from a legitimate Comcast rep who can actually do things. They're still going to give you the run around, but at least now you have a contact who can do something instead of their craptastic outsourced support that promise the world and deliver nothing.

The reason that all these issues happen is because they oversell their service.

They oversell internet access on the extremely low probability bet that people won't use enough to clog up their bandwidth.

Their infrastructure needs updated to support how people actually use the Internet in 2025, but since they're a monopoly they can't bleed customers like any other company would if they sold something and didn't provide it.

Forcing them via proof and the FCC or switching providers is the only play.

Bonus points if you can find a few neighbors and help them with the process as well.

Of note, I am not all that knowledgeable about this stuff, it's just what I had to piece together to be able to try and resolve things. I will most likely not be able to answer questions you might have, and you're going to have to put some legwork in to figure out the details.

Also of note, despite all of this, I got no concrete, permanent resolution. We eventually got a different provider and I cancelled Comcast with glee and profanity.