I think the added benefit of an OpenWRT router is, you get 3 more ports (for your TV, Playstation and PC), plus a Wifi network. And it’s really hard to break it. But a MiniPC with OPNsense, of course will be more powerful. And some more advanced things have been notoriously difficult to set up in OpenWRT, maybe OPNsense does it a bit better.






Sorry, I just saw the recommendations. I’m using a Matrix server myself. And it’s connected to the internet, since I use it 24/7 and on my phone, etc.
I guess technically, most protocols can be used in an internal network. But maybe you’ll need to put in some extra effort, for example if a platform requires SSL certificates or something like that.
I mean you could try… If it asks for a hostname, just put a local hostname in. Or the IP address. Or set up a DNS entry on the router. And see if it works.
Or try something like RocketChat, or depending how your team’s workflow is, maybe you don’t want a messenger. But some (online) collaboration platform more focused on documents, like Nextcloud.