I have my Plex on a NAT network, no public IP, but it's port forwarded for direct access with iptables rules and I also use haproxy and cloudflare for the frontend on a subdomain. Running your own virtual private server gives you complete control over. It is probably as you suggested a networking setup thing. The simplest way to run your own streaming setup is to choose a cloud provider that specializes in Plex media setups. Nothing wrong with my Plex server, running solid for years now. Once I reset the IPtables, it was just like any other VPS and I was able to use v2ray I found about the iptables issue from the oracle cloud thread at OGF. I dont use oracle cloud myself for plex but I do know that firewall configuration alone isnt enough to access services on oracle cloud. The issue in OP's case was due to iptables. Thanks to various streaming portals and services like Netflix, YouTube, Hulu, or Vevo, Plex users can play online content directly through their media center interface. I have few servers in EU that are accessible whenever I try. Launched as a freeware project in 2007, Plex has an impressive range of features and is undoubtedly one of the best media centers of all time. There must be sonething wrong with your plex server then or may be network it is on.

I get that message appear occasionally even though my Plex is completely accessible. Sometimes Plex lies about whether it can be accessed from the Internet.

tried everything and it now works, now gotta figure out which was the key.

Plex cloud hosting