Veeam B&R Connection problem via IPSec VPN

Try on backup client add a server IP in hosts table

 

Other reference

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam EndPoint Backup

https://www.veeam.com/kb2335

https://gist.github.com/vertigra/cb4d802cfe3548d9c92b9e2d87b25d66