I believe Sudoroom's IT infrastructure such as website, listserv, wiki and sudo humans
are hosted on Digital Ocean VPS.
Noise bridge has some collocation spaces in a data center where they host their website.
On premise hosting is not used for several reasons:
1. Both Hackerspaces are using wireless internet from Monkeybrains. Thus bandwidth is
limited. (Should be sufficient if it just scales to serve the community that actually
comes to the hackerspace).
2. Security and reliability: Data center is less likely to have power and network outage.
Although we are do-ocratic, it might be a good idea to have some access control around
critical infrastructures.
Sudo Mesh has a rack in their compartment(Visible from Sudoroom).
Thus to your question, I think the best option is to use existing VPS or a SaaS provider.
Also the closest FOSS alternative to discord should be Matrix, both are group chats with
support for rooms and spaces. Matrix rooms can also be bridged with discord rooms. I think
you are implying that forum is a better medium than group chats. I agree that group chats
are overused especially with the advent of discord. One thing we can do is to use the wiki
for more long-term and static information to complement group chats.