Have you tried hooking up your PS to the other family members connection? I would think that if you’re fine on their connection but screwy on your wired connection then perhaps an issue with your wiring? Is it an old place and maybe an old cable? Do you know what kind of cable? You could try getting a length of cable and see if thats better. From a customer service pov you should not have to be restarting your router all the time. They should be able to figure out whats going on.

If Xfinity goes down but your phone is working you could use it as a hotspot. You could also get a satellite net connection or a mobile hotspot device.