Why are most of my 4K video stream buffering?

[aj-plex]

Constant Buffering on Xbox One

Hi all, I am getting constant buffering on Xbox One and am at a loss on how to fix it. I’m running Plex Media Server on Windows 10 64 bit and the connection is USB 3.0 Ethernet adapter into home plug, then home plug other end into BT Home Hub 5. The Xbox is also hard wired to the hub. I have no issues streaming to other devices. What can I do to improve the situation? Thanks

So do we all need to buy plex pass too for it not to buffer on xbox?