noirelion covered a lot. Ill add a bit more.
I remember seeing some posts in the Tmobile forums regarding WiFi issues but i don't recall if it was related to root or specific roms. In any case, the fix for the issue, if I remember correctly, was to update the router firmware (it only effected a certain router brand, I dont recall which). I haven't run into this issue myself and dont use my phone to run my media center....though I should start to
FYI: Did you guys know that the S4 has a built in IR Blaster? That dot to the right of the headphone jack is the infrared LED (like the one on your TV/cable box remote control) and with the proper app (search for IR Remote) you can control most TVs, DVD players, cable and satellite boxes etc like a universal remote...no wifi necessary. That is assuming the app you use has the proper remote code....which is the issue I have. I can control the cable box with it and my stereo but not the TV because its old and I cant find a code for it that works