Live tv has weak signal and stuttering

I’m a newbie and have been working on setting things up. I have the HDHomeRun Extend connected to the Plex Server which runs on a Synology DS1813+. The client is a Samsung TV with Plex client running on an Amazon Fire. When I have the antenna hooked directly into the TV all channels are fantastic. When hooked into the HDHomeRun Extend, some of the channels are choppy, they are unwatchable. Any advice or will I be cancelling my Plex subscription and returning the HDHomeRun Extend. Many thanks in advance for any help.

I should of mentioned, everything is hardwired, no wireless.

What settings have you tried on the Extend? I have a Connect that I have tested with Live TV to a Fire Stick Gen 2 that I can direct stream TV shows. The Connect has no transcode capabilities and my server was not doing any transcoding since the Amazon Fire Stick was capable of direct streaming. I just got an Extend last week and have not played with it much using the Fire Stick. I did play with using my iPhone 7 Plus and found that setting the Plex DVR setting for the Extend to Medium Quality (540P) gave me the best stream with only 2 or 3 instances of buffering over approximately 30 minutes of viewing. All of the higher settings caused lots of buffering.