This Xenforo solution is really nice.
It's good to find a modern forum solution that you host yourself rather than it being cloud-hosted on someone else's server.
The only private forum that I've seen that was comparable to this one features-wise was the Jolla Sailfish OS forum (which I learned was 3rd-party/cloud-hosted anyway).
I look after a PHPBB kind-of on behalf of a friend, although I get plenty of use out of it myself too.
It's a very mature platform. It is what it is now and future updates will probably only amount to security fixes rather than ground-breaking new features.
But it does have the benefit of being free and open-source.
I wanted to suggest putting an favicon.ico file on the server so that the forum is easier to pick out from your tabs list if you keep lots of tabs open.