Backup failure with error 2074/2106

Hello All,

Have anyone faced backup failure with code (2106) Disk storage server is down ) /1: (2074) Disk volume is down where Destination target DataDomain

Our DD model is : DD670

DD Os is  - 5.4.2.1-423209

NBU version is :7.6.0.1 / Solaris 10

Frequently we get job failure with code 2074/2106, i check Diskpool and they shows UP

Error we see in DataDomain is :

: WARNING: MSG-RPC-00001: Rejected 35 connection attempts to port 2052 in the last 10767 minutes.

: WARNING: MSG-RPC-00001: Rejected 9 connection attempts to port 2052 in the last 930 minutes.

: WARNING: MSG-RPC-00001: Rejected 46 connection attempts to port 2052 in the last 527 minutes.

If anyone faced such issues and resolved , pleae share the resolution steps.