A computer with a modern operating system and networking software can host the wiki server. This combination of resources can be found in many places.
See also Federating Foreign Servers
# Computers
Laptops you already own.
Servers designed for many services.
Virtual Machines configured for one thing.
PaaS cloud services.
Docker containerized packages.
# Configuration
A host can run many servers and a server can serve one or many sites.
Development with multiple servers.
Farms with many sites served by one server.
Security for authenticating site owners.
Update with improvements from open source.