Able to reach server by browser, but not apps

[Tim]

It is only the tunnel feature of Cloud Flare which is against the ToS of Cloud Flare as they then have to tunnel all traffic, including video. Some common setups that people use for accessing Jellyfin is using tools like TailScale. Some people also rent a VPS somewhere and setup NGINX + a VPN tunnel back to the server (i.e., WireGuard). This method also allows for TLS/SSL certificate usage from something like let's encrypt as NGINX is used as reverse proxy. The former is easiest to setup but requires more setup on each client accessing your Jellyfin instance. The latter is more complex to setup but requires no changes on the client / user side.