Can you access your server using its local IP address (e.g. http://127.0.0.1:32400/web if you’re on the same machine as your server; http://[PMS IP address]:32400/web otherwise)? If not… what error message do you get?
Would you consider updating your server to rule out there’s some bug that has been fixed in the last 5-6 weeks (latest version as of tonight is PMS 1.23.6.4881)?
If you’re not able to reach plex.tv from within your home network this could be linked to a more generic issue in your network (e.g. some firewall/filtering or a bad DNS)