Raspberry Pi 3
Raspian Stretch
Plex Server 1.8.1.4139 (from this post)
Tuner is Hauppage 955Q (which is on the supported list and channels show up with w_scan)
I saw this post which says 1.7.2 solved the problem for the original poster. I am trying with 1.8.1
So I rebuilt the pi from the ground up, testing along the way. With just the Raspian Stretch installed, w_scan found channels. Then I launched a VNC session, installed Kaffeine and was able to scan channels, watch live TV and record it. Then I installed Plex server and am back to the spinning circle of not finding the device.
There is an option to enter an address manually. It doesn’t like the machine name, hostname, localhost, 127.0.0.1, the local IP or the public IP. Does it need a port number? Is there a service it is trying to connect to? Raspian came with the drivers for the Hauppage but there is no service running for that. Should there be?
Plex Server 1.8.2 was released yesterday for Pi/Arm: this link
That release fixed the problem. Plex now sees the tuner and is scanning channels without issue.