It doesn’t matter if it is a business entity operating under a government then you can never really know because gag orders. Centralized servers can be blocked. Telegram and Signal apps could have a back door. This is why open stack is important. And not just the code. Also encryption is default for p2p one on one conversations. It’s not in channels by default because it can complicate public use.
Yeah the main thing is that the ports and addresses can change and it’s nbd. From a firewall perspective, it’s impossible to block them all. Especially when the clients are doing mundane https requests. Even if the server goes down or partial connectivity, the channel can still be used.
It cannot be easily blocked especially if you use your own homeserver every homeserver replicates the channel and it can operate without the original server! That’s why signal and telegram are inherently flawed.
I can answer this! All matrix calls are over https APIs. Ports and addresses are stored in a text file on the base domain or in DNS txt entry.
It’s perfectly fine to host jellyfin online. Use a proxy server to enable TLS and do not use default ports 80/443. Use letsencrypt for free certificates. No need for VPN to access here either. Do not expose any other ports such as SSH on default ports. Lock down your jellyfin server and any other related services behind a VPN service and block access to Internet through other interfaces (except for port forwards on your ISP for jelly). Go high on port ranges since they typically aren’t scanned or blocked. Go dual stack for best results and don’t use your router address for IPv6 more than likely you have your own /64 choose a different address for port forwards. Do not assign this address to your internal servers. Use a reserved unrouted IPv6 range internally and do NAT6. Do not allow any raw IPv6 internet access