I also have Xfinity Blast but that is internet speed, not home network speed. 100mbps is too slow for today. You need a router that is gigabit speed (1000mbps). If you have rental router and modem, you need to know their specs. I own my own router and modem. Router is DOCCIS 3, router is gigabit dual band wireless. For streaming you need to use the 5G faster band either in a dual band or tri-band (AC) router. Router needs to be setup so that you can distinguish between the slow 2,4G and faster 5G – I never use 2.4G except for devises that do not carry video streams.
Hopefully, your 70" TV uses 5G signal as well. BTW, Netflix checks your bandwidth before sending signal, and with Blast you have top internet speed for Netflix. Why does your TV has issues with Netflix?.
There are plenty of issues with Plex showing video in full rez. See this thread of the past few days which I was a part of. Plex has big limitations other software/devices don’t have.
My best video streaming from NAS is with full rez ISO and MKV files to WDTV or to FireTV stick running Kodi when I can stream same kinds of files to FireTV as I can to WDTV. Both setups can handle DVD ISO and MKV files (from BD discs). Streaming to iPads and Kindles is flawless using the quality 5G wireless signal. Plex is an also ran which can only handle my lesser quality mp4 files of same videos.
