Have you verified the port forward is visible/accessible from outside your home network (e.g. using a service like canyouseeme.org)?
The log snippet isn’t showing any issues resolving the URL, so it doesn’t seem to be a DNS issue (though, not much can be said based on just those 2 lines of log).
Did you already have a look at the related troubleshooting support article?
https://support.plex.tv/articles/200931138-troubleshooting-remote-access/
There’s also a guide with some more details on how to troubleshoot remote access issues:
