SQL Backup is failing with error code 6

SQL policy deactivated? Why is 'Active' showing 'no'?

Policy Name:       MSSQLbackTOPICSCLUSTER

  Policy Type:         MS-SQL-Server
  Active:              no

Have you verified port connectivity (vnetd - 13724) and forward and reverse name lookup in all directions? 
Master <-> virtual hostname
Media server <-> virtual hostname

Have you verified that NBU Client service on cluster nodes is started as SQL admin with local admin rights as well as SQL rights?

For further troubleshooting, we will need dbclient log on active SQL node as well as bprd log on the master.