'Communication failed' message between DDs

Dear All,

I am using networker 8.0.2.6 and DD670 for backup and backup storage. I have two DDs, one as primary target and the other DD at a different site, the data replicates from primary DD to the other site DD. I have observed that on Management Station of primary DD the system state of replicated DD is howing as 'communication failure' , please refer to the screenshot

Whereas when I log on to the replicated DD, the system state of primary DD does not show as 'communication failed'

I have two types of devices on DD 1) OST 2) AFTD, I can see from Networker Management Console that ost devices are getting replicated, for checking AFTD file share replication I log onto DD Management Station to check the status and i find that they are not getting replicated

I am looking for the things that can be checked and done to resolve the issue.

Both the DDs are pinging and name resolution is working fine. DD OS is - 5.2.1.0-331816

Regards

tech88kur