Why is my internet so unreliable after a power outage?

A few weeks ago, we experienced a power outage that affected half of our house, but our modem and computers stayed on. Since then, my computer has had intermittent internet issues. Initially, the internet seemed to work enough for Steam but not for anything else. Restarting the modem fixed it briefly, but then it created problems for my mother's computer, which is directly wired to the modem. Even more confusing, when my father turned on the TV connected to an internet box, my connection dropped entirely.

This has been happening for a few weeks now, especially when I first start my PC, requiring me to unplug and replug my WiFi adapter. Sometimes, my connection lasts only 5-10 minutes before dropping, yet my adapter indicates a successful connection. Mozilla Firefox shows a server reach issue instead of a complete connection loss, and oddly, Discord remains functional for messaging. We recently replaced the modem, but the problems persist. I've tried various troubleshooting steps, including changing USB ports, using my phone as a hotspot, clearing browser cache, modifying DNS settings, and reinstalling adapter drivers. Despite these efforts, other devices occasionally lose connection too, and changing USB ports has sometimes triggered Blue Screen of Death (BSOD) errors. I'm really at a loss for what could be causing this. Any ideas?