Packet Loss

For some time now, I've been experiencing~1-4% packet loss when gaming with occasional spikes to 40%. It used to be only on the upload side, but is now on the download side as well. I assumed this was due to WiFi. I recently switched to an ethernet connection but I am still experiencing the same exact problem. I have tried so many different things to find the source of the problem but I am all out of ideas. Here's what I've tried:

Wired connection to PC

Different cables for modem/router

Different PC

All sorts of network settings on PC

Factory reset modem, router