Rocketloader is a technology used by Cloudflare to speed up page loading. However, this doesn’t work with all Websites, as I mentioned in another post (it’s been known longer, however it’s just a tech thing, not a bug).
WAF is a Web Application Firewall. You can read more about that here, but this is probably not the issue, especially if you don’t have one deployed.
A minimum TLS version would block devices trying to establish a connection via a lower TLS version. In that case, Plex would try to use the Plex Relay system. I think you would’ve noticed that.
Edit:
I’d try a reinstall (Plex Dance or another way) because I can’t remember what the culprit was. I’ll let you know though
