Thanks for your suggestion.  This was resolved with a network disconnect and connect on one of the 'Data' lans.
Odd issue appears and i can;t see any reasoning behind it.  We have a couple of vCentre Custers, configured with 2 VRPA appliances on each data centre location.  These are clustered and then cluster joined to the other datacentre site.  All been working fine for a couple of months, onboardsing VMs, replicating, recovering etc. We had a couple of storage changes earlier in week,  and had to reset some of the VRPAs, and now have got the error in the dashboard of: Data link is down for RPA 2 between clusters.  Clusters are still working, RP4VM is still functioning, but just complaining about this.  I cant see any config issues or anything flagging as a problem (and there has been no actual configuration changes that would have affected this.) and have checked against the other cluster which is configured the same with no issue. Have checked connectivity on the appliances and cluster through the CLI and all looks ok. On a final note, im not overly impressed with the logging and events in RP4VM - may just be me, but i dont think its great - this error showing on the dashboard for instance doesnt have a correlating Event log or timestamp i can actually see, which i dont thinki is overly helpful...and also doesnt leave me convinced this is still an erorr, although still show sont eh dashboard.   Any one with similar issues?  Thanks.  
RP4VM - Data link is down for RPA 2 between clusters