Hi @Alfred79 

Welcome to the forums.

I’m not sure I understand. Are you saying that the Veeam Server, which is off the domain is not able to backup VMs that are on the domain?

From the screenshot it looks like a connectivity issue. Are other backup jobs working correctly? Have you checked whether your proxy servers (if deployed) are accessible? 

Can your Veeam B&R server connect to your (I’m assuming) vCenter?

An easy way around this is to use the HOSTS file on the Veeam server to add both the FQDN and IP of the servers you are backing up.  Then test ping to the FQDN which should work.  I have had to do this at times with Veeam installs.

So, the hosts file will have something like this -

IP address        FQDN

FQDN              IP address

If you are using your internal DNS settings for your NIC, you can also have it search for your primary domain DNS suffix under:

“Internet Protocol Version 4 (TCP/IPv4) Properties” → “Advanced” (button) → “DNS” (tab) → Append these DNS suffixes (In order). 

Have you database on same vbr server? In this case you can rename It but at the end you need to use Sqlconfig utility (Sorry I'm writing from my phone and I cannot link the correct Page).

Hello Everybody, the problem is that the server is in workgroup, after the server join in the domain all work fine. But is better to have the Veeam server out of the domain in the workgroup. The problem is whit the user permission. Wath user permission i need to backup from workgroup to domain Hyper-v? Thanks

Oh @Alfred79 now question Is completely different. 

Domain or not Is tour choice BUT Veeam BP wants Is a different domain. Consider all security check needed ti have a secure environment 

You can check all users permission here for Hyper-V 

This was going to be my suggestion, but Chris mentioned hosts files which is also great for a recovery if your DNS servers are down/unavailable.