Backup exec transfer speed from one particular VM to tape slow

I have recently discovered that one of my VMware VMs transfer from disk to tape is V. slow. Other VMs are fine but this one has 100ishGB data and seems to only get to 113Mb transfer rate. I have followed the usual troubleshooting: copying from VM to backup server local disk but transfer still slow. Looks like it points to something other that Backup Exec but was wondering if anyone has come across this. The server has DNS on it (not primary) - Could this be the issue ?.

I have pushed out the agent again. The transfer rate used to be 1.3Gb /min. Only happened recently.