I had a problem on my router and here is a solution to pass over this problem. 

The problem : 

The wi-fi on my router worked but it wasn't connect to internet ( orange led instead of blue one ). I tried to plug the WAN cable directly to my computer to check if it was working : it was. So the problem came from the router. 

The solution :

Change the MTU parameters via the http://192.168.0.1/  Network -> WAN -> MTU Size. I changed it to 1430 and it was working again.

Hope I helped you : )