Radmin Version Compatibility
Remote Administrator 3.x is compatible with Remote Administrator 2.x. You can connect to Radmin Server 2.x with Radmin Viewer 3.x. However, some features and connection modes are only supported if Radmin 3.x is used both on the server and client sides. You won't be able to connect to Radmin Server 3.x with Radmin Viewer 2.x due to program design.
Radmin viewer 3.x -> Radmin server 2.x Allowed
Radmin viewer 2.x -> Radmin server 3.x Disallowed