Yes. There are specific IP ranges reserved for local networks, and others that are used publicly on the internet. If you want the details, see this thread: Server setup wizard not authorized - #10 by dbirch
Lately, I’ve seen quite a few posts where people were using public internet ranges for their local network. One side effect is that Plex won’t let you claim your server unless it’s on one of the proper private ranges (RFC-1918). With the recent increase in these cases, I thought it best to confirm that first before digging into additional troubleshooting.
(Sorry for the delay in responding—I had stepped away for dinner.)
