Hello @nicolay ,
welcome to the community.

First of all, which version of VBR are you using?

Is there a firewall between the VBR server and the Hyper-V host and are all needed ports opened?
https://helpcenter.veeam.com/docs/backup/hyperv/used_ports.html?ver=110

Is this a Hyper-V server or a physical server you’re trying to protect with an Agent? I think you meant to say VM instead of VN but just want to clarify!

i am using VBR ver 11.0.1. will have a check again to those ports then

physical server but has the Hyper-V feature enabled as we are going to have a VM (and not VN, typo) running on that server

Ok, there are several patch levels to the 11.0.1 (or 11a) version.
The latest is 11.0.1.1261 P20220302

that’s the version i am using
 

Thanks for confirming, btw it looks like your username is formatted incorrectly, it states you should specify either DOMAIN\Username or HOST\Username if the server isn’t domain joined. Your username just says “Administrator”

already tried with host\username as well, same result

OK, then the obvious things are checked
Did you have a look at the used ports list?

will do that shortly

Here’s the ports you need: https://helpcenter.veeam.com/docs/backup/vsphere/used_ports.html?ver=110#microsoft-windows-server

As the server isn’t domain joined, your default domain GPOs aren’t configuring your windows firewall which, just like @JMeixner is suggesting, I believe to be the problem.

hi there, apologies for not replying all these days.

after double triple checking, nothing is blocked from both sides and now i am able to ping the remote server and ping from the remote server.

now i get a pop up message saying that it cannot find it  although i am connecting to the server via RDP. so i am not sure what is going here, see below picture.

Hi @nicolay, RDP is a separate process & port you’d be trying to reach however. from the VBR server try to connect to the admin share using the credentials you’ve specified, to do so you’ll need to open file explorer and put the address to “\\<server name or IP address>\admin$”.

Let us know if this works.

Seems to me that this issue still persists. This issue could be as a result of multiple factors.

The error above is clear! Server does not exist! Check firewall settings.

- Also ensure you have the right permission to perform a domain join. Like you said, you have been performing this. Therefore, you can over look this.

- Required ports may need to be opened by the network team since the device is in a remote location. You can test if all ports required via PowerShell to be completely sure. They can claim all what they want, you must test this.

hi there, apologies for not replying all these days.

after double triple checking, nothing is blocked from both sides and now i am able to ping the remote server and ping from the remote server.

now i get a pop up message saying that it cannot find it  although i am connecting to the server via RDP. so i am not sure what is going here, see below picture.

 

Have you also checked to see if you have the rights to manage this device? Take a look at the event log for more  As already advised, kindly ensure you are using the right account format. In this Posts, @Mildur resolved a similar issue in the past. Kindly take a look: 

Do not forget to mark any of the comments that helped you best in resolving your issue.