When surfing the net great for a while then it slows

Great for a while then slows down to the point that it takes 10 times the time to do anything. This happens to all devices hooked to my network which is wps/wp2 encrypted but it's still like someone is getting on the network and using all the data. The other thing is I've shut down one device at a time and I swear they are all paired together. Sometime unplugging my smart tv will then unlock the system and everything goes back to great again other times it's my IPhone 4 or. 3. Other times I will reset the router and that fixs it. I fix things for a living and are very good. This is some kind of hacking program or emmbeded software of some sort. My theory. I build and fix laptop/ desktops and have worked with them since I was 8 and my dad brought home an attaché computer. That's when I started writing dos programs. Does anyone have knollege of type of behavior on networks. It's spurattic but sometimes I have to shut everything down wait hours then it all good again. I am lost moved 3 times in two years and been on different equipment at each place. And yes it's happened at all three places. I fix them I don't hack them so I am unfamiliare with how hacking programs work. Please help