What version of Veeam are you using?  What OS is it installed on?  Did you check the logs - C:\ProgramData\Veeam\Backup

Also I would search the forums as well https://forums.veeam.com

Worst case create a support ticket.

Hi,

Server 2019, Veeam ver 11.0.1.1261

Logs do not shed any more light on the cause unfortunately, as least as far as I can decipher.

Any reason you have not upgraded to Veeam 12.3?  That version is fairly old and out of support.  You may want to consider upgrading and then check if the issue persists.

Yes, I’ve been considering that as well. I think I’ll do that before further diagnosis. Will update accordingly.

Hi ​@robns,

What exactly is the task that fails? I know port 11731 from an agent deployment scenario so maybe Veeam is trying to deploy an agent to a target system?

In case I suggest right there might be either permission errors on the target site or a local or physical firewall is blocking ports. Maybe you should check the situation on the target as well if there were changes made.

I also agree with Chris, you should consider opening a support ticket.

Best

Lukas

Agree with Lukas. Needing to know what task you were/are doing?

Is this error in a Backup Job? Replication Job? Copy Job? Agent? Or, are you trying to add a Veeam Component or Managed Server? Needing more info on what you’re trying to do ​@robns . Let us know if upgrade resolves your issue.

Best.

Sounds good.  Let us know what happens after updating to 12.3 and the backup status.

Hi Guys,

Haven’t update the version yet but I found the issue. It was mentioned here: https://www.veeam.com/kb4495

“Note: Use of a local account other than Administrator will likely fail; see KB4185.”

Once I used the server’s local Administrator account (this is a member server, not on a domain) for the physical server in Veeam > Inventory > Physical Infrastructure > Protection Group, it successfully scanned the server and backups now run. I was using an account that was a member of the administrators group. For some reason, this stopped working.

Great to hear you found the solution and thanks for posting it here for others.

Glad you were able to solve your issue. Thanks also for sharing your resolution. 

Best. 

Purely for future visitors of this thread, in my case I did the Security & Compliance process on my backup server and fixed all the issues the day before the backups failed with this error (Processing Error: Failed to connect to :11731), my first try was to add the systems that failed to the hosts file on the backup server.  Problem solved for me.

That’s a good comment ​@SomewhereinSC . The “Best Practices Analyzer” (now S&CA) has significantly grown and to get all the items “green”, a lot of modifications to the VBR server need addressed, which could of course lead to communication issues with Veeam Components or source VMs. Makes sense. Thanks for sharing!

Had this same issue after implementing the recommendations suggested by the Security & Compliance analyzer. Suspected it was a DNS issue, confirmed by running test-netconnection -computername name -port 11731 in PS (which gave me the message “WARNING: Name resolution of ‘name’ failed”). 

Since my backup server isn’t in the domain, I had to manually add my domain as a dns suffix (see steps below, credit to Copilot). Once this was complete, I was able to disable NetBIOS without disrupting the connection between Veeam and the physical servers that it backs up. 

1. Open Network Connections:

   • Press Windows + R, type ncpa.cpl, and hit Enter.

2. Right-click your active network adapter and select Properties.

3. In the list, select Internet Protocol Version 4 (TCP/IPv4), then click Properties.

4. In the new window, click Advanced, then switch to the DNS tab.

5. Under DNS suffix for this connection, enter the suffix you want to use (e.g., company.local or internal.domain.com).

6. If needed, you can also check “Append these DNS suffixes (in order)” and add any other domains to be searched.

7. Click OK all the way out to apply changes.

You might also want to flush DNS afterward using ipconfig /flushdns in Command Prompt to clear any cached settings.

This article was also helpful: https://www.veeam.com/kb4469