I have a standalone Windows server (VM) hosted at a third-party data center that is shared/used by multiple orgs. As a shared server, maintaining the server will be a collaborative effort by select IT staff from some of the orgs. The server is running a single, very specific service and is pretty much set-it-and-forget-it, so the remote access is mainly for periodic maintenance such as Windows updates, disk clean-up, etc.

I'm looking for a solution for these IT folks to be able to securely connect to this server over the internet preferably without setting up a complicated VPN infrastructure. The data center operator is willing accommodate requests (opening up ports and such) to a certain degree but installing additional equipment (VPN appliances, etc.) is probably a no-go.

One-time costs would be acceptable but we'd like to avoid subscription-based solutions as it's difficult to split the bill among the organizations due to administrative reasons.

Within my org, we are using RemotePC to access certain isolated machines that can't be part of our RMM. I thought this might work as adding one more machine costs nothing, but it requires adding collaborators as users in an existing RemotePC account which creates a dependency on a single org. If my org dies, so too does the account, and access for all provisioned users.

Does anyone have any suggestions in this scenario?

Thank you in advance for any advice and insight.