UnityVSA failed replication connection from physical Unity

I have installed the UnityVSA Community Edition.  I'm trying to set up an Asynchronous File replication from my physical Unity 450F to the UnityVSA. 

The connection fails in the 4th of 5 steps - "Refresh local system connections on remote system". 

The error description says, "Although the remote system is registered, the connectivity validation has failed. Check for any network connectivity issues, and also ensure that the time skew between the systems is less than 10 minutes. Once fixed, run the verify operation on the remote system to resolve this issue. View alerts related to the remote system connections for more information. (Error Code:0x6500128)"

The times are identical, and as far as I can tell, network communication is good.

(I tried a connection between my 450F and a 550F and that worked fine.)

The 450F has 2 SPs, of course, and therefore has 2 interfaces.  The VSA only has only one SP and one interface. 

Is that my issue?