Is your server still linked to your account?
You getting offered to “add media” / “download a server” implies the server might not be claimed and therefore not showing up anywhere except if you access it through its local IP address. This could e.g. have happened if you changed your account’s password and opted to sign out all devices (which includes the Plex Media Server).
If you’re indeed having a remote access issue, you might want to take a look at this guide to troubleshoot that (or to pin down a potential issue to get further assistance).
