Had same problem and finally hopefully solved it.

Seems I have no trouble streaming live TV (using real player on N810) on local wifi network at home to my N810 but when connected to BT Sprint phone it had codec problem.

I now use flash player on N810 as mentioned and make sure your server computer has UPnp and media server checked. Cant prove if these checks actually make a difference but can't hurt. Make sure you have latest orb upgrade version on home computer and make sure ports are forwarded and press the check button to confirm.

Hope this helps - still testing