Discourse Forum Hosting
Discourse is open-source web forum software. There's nothing complicated about it; users can post titled "threads" and other users can reply in a discussion. Discourse offers lots of admin customizations and themes. There are also a variety of user settings, like avatars and reply notifications.
Since a picture is worth a thousand words, you can try the demo for free to see if it's what you're looking for. Our instances are locked in containers for security and can be served publicly or over a VPN or internal network.