On-prem installation

Can Jitsi work on-prem without internet connectivity? what are the requirements?

sure, why not ? needs TLS though, since it’s a web software. Best way is to get a wildcard certificate for a real domain and create an internal address validated with the wildcard certificate.

Can I deploy jitsi on windows server on-prem?

install hyper-v if necessary, get a recent Ubuntu LTS release (18 or 20) image, use quick install, add wildcard certificate, and solve the network connectivity problems (port forwarding)

you can deploy it on docker & open ports. You can install a wildcard acme cert OR use a reverse proxy