I’m using my old desktop from 2010. There’s no such thing as a server that can “do it all”, but any computer from the last 10 years would probably be a fine place to start. The more you do, the more likely you’ll be to hit some sort of performance limit, and by that time you’ll know more about what you actually want.

In short, find old cheap/free hardware and start playing around.

Ooh, or my other trope: be a cleric with heavy armor and a shield. On your first turn in combat, walk out in front of everyone, cast Shield of Faith, and take the Dodge action. As a free action, yell “come at me, fucknuts!” If you can pick up the Shield spell, you’re mostly invulnerable, and it’s pretty much viable at level 1.

My personal favorite aspect with respect to combat is, “I look around, what objects and furniture are in the room?” Then proceed to use that stuff in combat. Long rug? I’ll attempt to trip the opponent by pulling it up. Chandelier? Yeah I’ll throw a hand axe and try to break that chain. Some DMs thrive off of it, some are put off.

I’m not an expert, but any time I’ve needed to do this, I set up my own router as a client to the parent router, and I set my router (client) as the DMZ in the parent router. Effectively you end up with two routers that are both (more or less) connected directly to the internet, without the two networks messing with each other. It’s also minimally invasive to the parent router (even old stock firmware has always had a DMZ option).

The tricky part then is using the wireless connection as your “WAN port,” rather than a physical one. In which case, as long as you can install OpenWRT on it, you should be fine.