I have seen a lot of companies, sites, non-profits move to Discourse[0]. It is customisable, low-cost, and has a lot of features which makes hosting a forum really easy and effective. This is a nice alyernative to hosting forums yourselves and Discord.
Excuse me? $100/month and it's a nice alternative? Guess I was expecting something open source so was a bit flabbergasted.
Discourse is open source: https://github.com/discourse/discourse
The plans shown on the pricing page are managed plan. You can install it on your server without problem.