This document talks about backing & restoring NSX-T L2 VPN autonomous client configuration.
We assume you have a working NSX-T L2 VPN Autonomous Client with vlans extended to VMC SDDC.
To backup the configuration, login to VPN client via UI and navigate to backup/restore tab. Click on backup post entering pass phrase. It will take close to a minute and you will prompted to save backup.tar file.
Taking an assumption, the L2 VPN VM has crashed and you do not have Image backup. We need to deploy new L2 VPN and restore the configuration.
We need to make sure the old L2 VM is powered off and the new VM has correct vNic mappings
Login to the L2 VPN client via UI and click on backup/restore tab. Browse the config file, enter the credentials and hit the restore button. It will ~one minute to restore the config.
You should see a similar screenshot like below.
The connectivity should be back to Cloud VM's (on extended networks) from OnPrem.
If the new L2 VPN VM has a different management IP as compared to old L2 VPN VM ; then post reboot new L2 VPN VM will fall back to management IP as old client.