When performing Veeam Explorer restores connecting to a service provider, sometimes these restores can fail with a Connection Failed message.
Looking in the Veeam explorer logs there will typically be references to a version mismatch. Ex:
4/26/2023 1:10:47 PM 20 (11320) Connection failed
4/26/2023 1:10:47 PM 20 (11320) Error: Incompatible Veeam Backup for Office 365 server version (received: 11.1.0.600, expected: 10.0.3).
This is due to a different version of the Veeam explorer being installed on the tenant’s Veeam Backup and Replication server than the service provider’s Veeam for Microsoft 365 server.
The solution to this is to download the same version of the Explorers currently installed on the service provider’s Veeam for Microsoft 365 server. This can either be downloaded from Veeam in the form of the Veeam for Microsoft 365 installer .iso or by contacting the service provider and asking for the individual Explorer installer .msi files.
Once downloaded and installed. Try the service provider explorer again and the “Connection Failed” error should be gone.