Is a server/client setup possible with Duplicati?

Agreed if this means being the central administration server. If it means web-serving to a central server, it doesn’t need to know it’s doing that, however its web server only takes incoming connections, so it needs help if that’s hard to have. This probably depends on barriers such as firewall, NAT, company security, etc. Duplicati on a headless Linux box can be managed through either direct browsing, or SSH port forwarding. Reverse port forwarding through ssh -R or PuTTY plink could go out to bring remote port back to Duplicati.

The dumb storage destination seems to be the assumption of CloudBerry MMS too. The layout difference appears to be that there’s a managed backup site that works with both the on-client backup agent and the service provider. Duplicati (with its focus on open-source software, and not on sale of services) lacks this, preferring direct access from browser or Pectojin’s CLI client to the Duplicati server on that specific client.

Agreed. Depending on your needs and environment, it’s either pretty easy (if you can connect into clients), or takes some network work to set up. Monitoring status centrally is somewhat aided, thanks to third-party software which builds on built-in reporting options. Examples include duplicati-monitoring and dupReport.

Your central server might be an SSH server and a browser to go to SSH tunnel to Duplicati of your choice, however if you want less client autonomy and more centralized scripting, have the CLI client run the show. Unlike the client that ships with Duplicati, the Pectojin client works through a lower-level API to web server.