Paused devices, failed connection, unknown devices connected that I do not own

I have three problems 

1. I have devices connected to my router that I do not own even if I wanted to forget the device I can’t unless it’s disconnected from my home network so I can only pause them

2. my laptop says paused but the Xfinity app says connection strong and that it’s unpaused. I’ve done reset on both ends of my computer and router…nothing works 

3. Same thing with The PlayStation 4 “strong connection” but I cannot connect my PlayStation to the internet. I looked into PlayStation help and I get told it’s the router issue. 

i have restarted the router I have just gotten a new router. This issue is still happening