NVP-vProxy: Failed to disable storage migration for virtual machine "VDDK Error: 18000: Cannot connect to the host"

New installation with IPv6
All backups fail with the error message:

2017/01/24 14:44:18 TRACE:  [43] Disabling storage migration of virtual machine "vm-52676" ...
2017/01/24 14:45:18 WARN:   [43] Error disabling storage migration, retrying, error: VDDK Error: 18000: Cannot connect to the host.
2017/01/24 14:48:25 ERROR:  [43] Failed to disable storage migration for virtual machine "vm-52676": VDDK Error: 18000: Cannot connect to the host.
2017/01/24 14:48:25 ERROR:  [43] Error disabling storage migration for virtual machine "VM-AD-5".

Network connectivity to vCenter is over a dual-stack (IPv6 and IPv4) network. The vProxy resolves the vCenter hostname to its IPv6 address. As per the NetWorker VMware Integration Guide, vProxy appliance configured with dual stack or IPv6 only is not supported.

Steps to verify the problem:

1. Log in to vProxy as admin and sudo to root.
2. Test lookup:

   nslookup -q=any vm-vc2.ad.local	

   • If the answer has any AAAA address (IPv6 address), then you have verified the problem described in this KB. Proceed with the workaround.
   • When the lookup does not work, fix the domain name service (DNS) resolution. In this case, the workaround described below is not needed.
   • If lookup works, however does not have any AAAA address- this indicates a problem with connectivity. Further diagnosis is needed. In this case, the workaround described below is not needed.

Workaround: To setup preference for IPv4 lookups

1. Log in to the proxy as admin and sudo to root.
2. Run command to prefer IPv4 lookups: 

   echo "precedence ::ffff:0:0/96  100" >> /etc/gai.conf
   

If the workaround does not resolve the problem, follow these steps to UNDO workaround:

1. Log in to the proxy as 'root'
2. Edit file: vi /etc/gai.conf
3. Remove line: precedence ::ffff:0:0/96  100
4. Save file

Refer to KB Article 000495114 for the error: NVP-vProxy: Error disabling storage migration, retrying, error: VDDK Error: 20005: The operation has been disabled by the guest operating system.