Unity 600 - Initial configuration for sync replication

Greetings,

I am trying to use sync replication between two EMC Unity 600 storage devices using the FC ports.

What I have done so far is to configure the IP adresses of Management, Sync management and FC ethernet ports.The management and Sync management ports are connected to and ethernet switch.

For the FC Ports (which is used for the sync replication) I have tried every possible cabling I can think of. First I head-to-head connected the SPA ports of each unity, didnt work. Then I tried head-to-head connecting SPA to SPB ports, didnt work. Then I tried installing a DELL N4032F FC Switch in the middle, once again it didnt work. Always the same error as explained below.

3 Dell EMC engineers have remote connected to check the configuration and they said everything is as it should be, yet they can not explain the problem.

The error I receive is that when I start the connection verification, the fourth check fails.

     Register remote system on local system - Completed

     Register local system on remote system - Completed

     Refresh remote system connections on local system - Completed

     Refresh local system connections on remote system - FAILED

     Validate connections on local system - Not Started

The explanation after FAILED is - 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 it reun 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)

It is highly unlikely that the problem is caused by a time skew, as the same NTP server is configured to both of the Unity appliances, and ı can confirm time skew is not an issue.

When I go to Protection and Mobility - Replication - Connections and have it verify and update the connection, I receive the error:

code: 0x650015f. states: Ensure the fibre channel connection is up and re-run the verify operation to resolve the issue.

Considering the FC ports are connected head-to-head I dont understand why It wouldnt work. The two Unities are literally next to each other connected with an FC cable?

I ran out of ideas what could be causing the connectivity verification to fail.

Any help would be much appreciated,

Thank you.