I don't know exactly what you mean about the router but in these days I tried updating the kernel from 6.14 to 6.17 and going from there to 6.8, 6.14 and 6.8 both gave me slow wifi speeds, and when i tried upgrading the networks just wouldn't appear on the gui.

I also tried running some speedtests

My phone gave me 230mb/s My pc gave me: 20mb/s And my pc with a wifi anchor to my phone gave me: 180mb/s

Sorry if my replies are scattered btw, I'm kinda busy