Extreme latency spikes past two weeks. New modem, new splitter, and ground checked by tech none fixed issue

Hey guys, so I'm having a really frustrating problem that arose about a week ago. In fact, this issue has happened ever since the 15th when Xfinity randomly texted letting me know they discovered a problem in my area and were working to fix it.

"Hi it's xfinity assisant. We've identified a network performance issue that may be affecting your xfinity service and needs to be repaired right away. We're actively working to fix it by (date and time). We'll do our best to minimize disruption in this area. During this time you could experience a service interruption at (my address). We apologize for the inconvenience and will text you when the issue is resolved."

I didn't lose service to my knowledge any that day, however, ever since then I've been having massive latency spike issues where I lag very bad in games, sometimes videos buffer, etc. My speeds are fine just to clarify, it's strictly just latency.

So I called Xfinity and the rep was super nice and told me she could see the instability on her end and that she was sorry for the inconvenience that it wasn't a problem she could fix but would have a rep come out to fix. Que to today, the rep comes and he replaces my modem, checks my outside ground, and even replaced my splitter he said with one that has some chip in it or something. Unfortunately though, this did not fix the problem. So I've been running long form latency tests with https://packetstats.com/ just to have evidence of these spikes (even though I already knew because obviously I am having performance issues, and some games I play display my latency while I'm playing). The problem happens no matter if it's ethernet or wifi.

So I called again today, but this rep was honestly kinda rude and was basically trying to gaslight me that he can see on his end that I'm having no issues lol. He kept saying "I can see your service is online from here", and I kept trying to explain that my problem isn't that my service isn't working at all, but that I'm having awful latency spikes, and that I'd be more than happy to send him the proof (he declined this offer). So now I'm turning to this forum as I don't know what else to do here.. My internet ran perfect for years until now.

Here are some results of these long-form test:

Ethernet 12 minute test:

https://gist.github.com/msilvers73/44439666ee844c328fb2a87290884200

(Note: Unfortunately the graph only lets you see 5 minutes, so the real bad spikes were not caught in the graph, but take note to these, the worst spikes so far:

18322/01/2026 8:58:03 pm3202
22/01/2026 8:58:03 pm2689
22/01/2026 8:58:03 pm2208
22/01/2026 8:58:03 pm1723
22/01/2026 8:58:03 pm1289
22/01/2026 8:58:03 pm1169
22/01/2026 8:58:03 pm656
22/01/2026 8:58:03 pm183

Ethernet 5 minute test:

https://gist.github.com/msilvers73/0c945b5fe4e0e4090a3d7e25d7d9d85b

Wifi 15 minute test:

https://gist.github.com/msilvers73/1fd7dd70b09406a883da422383c1ef02

Thanks so much, and if there's any more information that I could provide that may help, I'd be glad to do so.