It seems my JU6050 TV (and perhaps other Samsung TVs as well?) doesn't really support IPTV. I have an m3u list of about 11 channels that are important to me, all of them are displayed just fine (basically in HD) on every other device, such as my computer and my android phone. But on my TV, some of them are significantly downscaled, so the sound is okay but the picture is really bad. I tried it with different apps: Plex, SS-IPTV and SIPTV. I get the same problem with every app and always with the same sources. Since all of them just forward the stream to the TV, it seems obvious that the OS (Tizen) is causing the problem by failing to deal with the streams properly (the same Plex server, when used on my phone, works just fine, but Plex doesn't transcode the stream).
I guess this is a pretty bizarre question, but did anybody else notice such problems?
Tizen TV doesn't support RTP/RTSP protocols.
Also UDP is not supported but you can watch UDP IPTV by setting UDP Proxy in Router.