i HAD the same problem....heres how i fixed it....and it was easy! the problem had NOTHING to do with my router........it was the wiring. i knew this cause my local network still worked when the tv was on....just no internet cause it knocked out my DSL modem.........heres how i fixed it....
its a new 51" plasma 3D smart tv samsung. i have DSL and i noticed that when the TV was on, the DSL didnt work.....or was extremely slow. the plasma tv replaced an lcd and i never had this issue with the lcd.....i narrowed it down and it was definitely the TV. i thought maybe the tv was causing some kinda weird electrical issue with my modem so i tried running an extension cord from the tv to every other outlet in the house and the DSL still didnt work when the tv was on. the plasma tvs are known to interfere with DSL because they give off RF. so after i tried that i figured the problem had to be radiated RF from the tv or screen itself. so i went into the attic and saw that the phone lines not only run directly above the tv, but that it was wired with old-ass flat wire. so i went and got cat5e cable and went into the attic and re-routed the phone lines and cut off the flat cable, replacing it with the cat5e.....instead of just replacing the wire, i routed it around where the tv is also so that the wires were as far away from where the tv is as possible. spent nearly 2 hours sweating my ass off in the attic and viola!!!!!! FIXED!
turns out the high level of RF the tv gives off added to the fact this place was wired with ancient wiring.......the old wires were just a huge RF antenna. the cat5e is coiled and is shielded from RF and cross-wire interference so it now runs great. and now the tv streams and all that where as before i couldnt even get it connected to the internet for obvious reasons...TV on=no internet.
DONT ditch the TV! its the wiring! you might even be able to just pick up the existing wires and lay them away from the ceiling of the room where the tv is if theres enough slack. but if you have the old flat wiring...get a spool of cat5e and either replace the wiring completely...or just splice it in above the room where the tv is adding enough slack so you can put some distance between the tv and the wire. worked for me! now im a happy 3D plasma smart TV streaming fool!!! hahaha
Edited by deleted (Sat 19-May-12 06:17:49)