Need to fix “Error parsing allowedNetworks”, the value you have in there is wrong and formatted incorrectly.
I would also go to http://my.hdhomerun.com/ and make sure that your HDHomeRun’s firmware is up to date. It doesn’t seem to be outputting streams Plex can decode.
Looks like it was the firmware. When I installed the HDHomeRun software, it automatically found that my tuner was woefully out of date and installed 20200521