Virtual Machine Backups Suddenly Got Slow

Hello,

In December, our backups of VMWare full virtual machines suddenly slowed way down. At that time a staff admin recreated datastores and bumped the VMFS version from 5 to 6. There were no other changes that I'm aware of.

Agent based backups run fine. Only Virtual machine backups run poorly now. It doesn't matter whether I backup to disk or tape, they never achieve a rate above 300 MB/min.

Ideas on where the bottleneck is? Something is limiting the communication from Backup Exec to vCenter. I have a case open with support, but they are not figuring it out.

I run BE 21.4 on a physical Windows 2016 server. Backup targets are NAS appliances and direct attached SAS tape drives. The server has teamed NIC that connect to three VLAN's: data to servers, second to NAS appliances, and third to underlying SAN appliances that host our VMWare environment. Our VMWare is old: 6.5. 

Thanks for your help. Ray