Is the Nvidia Shield powerful enough to use as a Plex Media Server (Live TV/DVR)?

What quality level can I expect to use with an Nvidia Shield streaming via wifi to a Roku Express? The PC I setup for streaming live TV and DVR recorded shows freezes and buffers unless I set the quality level really low. (Signal strength is excellent and I have no problem streaming Netflix at UHD resolution.)

So far my Plex DVR experience has been one disappointment after another. With all the money I’ve already spent, I don’t want to shell out the money for an Nvidia Shield only to be disappointed yet again.

Unless you built a low end PC the Shield will not be as good as the PC in overall functionality.

What are the specs on the PC?
Is the PC connected to a switch or your router with a LAN cable?