PC and TV, tried it on WIFI also, works fine here.
What type/brand of WIFI router do you have? And is there a way on the TV to check the WIFI signal strength?
The thing with the router WIFI security is to keep your neighbors from piggybacking on your WIFI, if you live in an apartment or housing tract then this is a common problem.
Some ISP's will throttle your internet speeds back when you get to the top of your bandwidth allotment, you may not use all of it but the guy next door may.