As long as you can map a share to MAS90 and you can hit the Sage ports (assuming its Advanced or Premium), the Sage client will be able to connect. I have seen this done on standalone desktops. Printing becomes an issue but you can always print to PDF.

You need Windows share permissions (ideally without having to rely on something like a mapped drive with alternate credentials, which is not the most reliable strategy), plus (as Mario states) if you are running one of the client-server versions (not Standard), access to the associated port (where some firewalls can be used to control access based on domain).

The only issue I've seen is with BOI and Premium using something other than a physical path for the Init() call.