Go into your internet settings & change the IP addresses of your console.
If you have a few devices connected to the net (phones/tablets etc.) you should check that you are choosing one that isn't already taken by something else.
I.e. If your console is 200.100.123, then change it to 200.100.125. Once done switch off & reset your router. It should reconnect automatically when you power on. If not you'll have to manually change in your router settings.
It can be a ball ache but it worked for me when my son upset a modder on Minecraft XB360 & couldn't connect with any multiplayer games. Think the tw*t DDOS-ed him.