A while ago and elsewhere @u_ne_korn mentioned using Bluetooth mesh networks for SF larps. In a similar vein, here’s a thread on larp reddit about getting data signal at larp venues, which includes some very useful comments on how to set up a local IT structure:
This is mostly geared towards SF or modern games where you want to have in-game networks, or access to the game website in play.
On the “host everything locally” front, I’ve thought about using a Piratebox setup for that sort of thing. Basicly a cheap wall-wart wifi router running a basic web-server (PirateBox itself is set up to be an anonymous file dump, which is great for Cyberpunk games, but you can set up a webserver instead).