I've been running a synapse server for a few years using https://github.com/...

I'd highly recommend the above Ansible playbook as it makes it easy to manage not only synapse but also to manage a bunch of bridges and bots if you have the need for them. I have a bunch of rooms that are bridged to Slack for my bozo friends that refuse to use a cool open-source alternative.

Can you share your firewall config? It could be that the firewall isn't allowing packets to be forwarded from the tun/tap interface on the router to the LAN interface or vice versa.

Can you ping the ssh server from the phone?

If they are on the same l2 network then your options are basically either to use nginx ACLs or a local firewall on the nginx host since the traffic wont traverse the firewall.

Something like iptables -I INPUT -s 1.2.3.0/24 -j DROP on the nginx host should work

If you want some fun "sports" games I'd recommend:

• Super Blood Hockey
• Super Slam Dunk Touchdown
• Regular Human Basketball (Great local co-op game)
• Windjammers 2
• Lethal League 1 or 2

As a protective measure, you could block your local synapse server from federating with matrix.org and that should keep anybody from joining any of the giant rooms on the largest matrix server.

I'm hoping Earth Defense Force 5 goes on sale so I can pressure some friends into getting it to play with me.

Prey is amazing! One of my favorite games.

Does Caddy come with the ionos dns challenge plugin built into it or do you need to compile it with the plugin?

https://caddyserver.com/docs/build#xcaddy

Saryn is really good for farming affinity in Sanctuary Onslaught which can be pretty useful early-game when you are leveling up a bunch of throwaway weapons to get your MR up.