The error "NBDERRNetwork_Connect" occurs when there is instability in the ESXi/vCenter network during VMware backup/replication/recovery while attempting to read VM’s disk data.

To resolve the "NBD_ERR_NETWORK_CONNECT" error, follow these steps:

1. Check the nslookup of the ESXi server from the BDRShield agent and vice-versa.

2. Verify if you can telnet to port 902 of the ESXi server from both the BDRShield agent and vCenter.

3. Examine the network connectivity of the ESXi host.

4. Ensure that the TCP ports required for the VMware agent are open. The following ports should be open in the hypervisor:

1. Port 22
2. Port 80 and 443 (if not customized, use the custom port)
3. Port 902
   

5. Confirm that the datastore (iSCSI, NFS) added to the ESXi host has stable network connectivity from the ESXi host.

If the issue persists even after following the above steps, please contact BDRShield support. Provide them with the backup log and vSphere log of the job to facilitate a more detailed investigation and resolution of the error.