To troubleshoot the cause for the VPN disconnections between VNetGW1 and the partner site, you should verify that the partner’s VPN device is configured for one VPN tunnel per subnet pair. 

To resolve the VM2 routing issue, you should modify the IP configuration setting of the Azure network interface resource of VM2. This will ensure that VM2 can communicate with other resources in the virtual network.

Troubleshooting connectivity problems between Azure VMs involves several steps such as checking whether NIC is misconfigured, whether network traffic is blocked by NSG or UDR, whether network traffic is blocked by VM firewall, whether VM app or service is listening on the port and whether the problem is caused by SNAT1.

BOX 1 = Download new credentials from Recovery Service vault: This error message indicates that the backup agent is unable to authenticate with the Recovery Services vault using the existing credentials. To resolve this issue, new credentials should be downloaded from the Recovery Services vault and then updated in the agent settings.