Gregory's Server
To add two more thoughts:
One is, i think modern people can non longer conviently use a forum because they have non longer PCs and Laptops, experiencing their whole communication to be something scrolling through a tiny phone screen
The other is, i use a lot of niche forums, and i miss myself a chat option in them. This might be one major thing we fail to do, to integrate XMPP or Matrix as an "quick message" button to a Forum and give every user automatically an account there