Hey Checkyourlogs Fans,

When working with Veeam Backup & Replication (VBR), WAN Accelerators are crucial in optimizing backup and replication traffic across wide area networks. However, sometimes backup jobs fail because the WAN Accelerator service is not running, which can be frustrating to troubleshoot. The good news is that there’s a quick and easy way to identify if a Veeam WAN Accelerator in your infrastructure is down using a simple command.

Identifying Blocked Traffic with Netstat

One of the first signs that a WAN Accelerator might not be running is backup jobs failing unexpectedly. Instead of diving deep into log files, you can quickly check for blocked traffic using the netstat command on your VBR server. Running the following command helps detect traffic that appears not to be getting through and returning a SYN_SENT state:

netstat -ano 3 | findstr "SYN_SENT"

This command continuously monitors network connections, filtering for connections in the SYN_SENT state, which indicates an attempt to establish a connection that is not being completed.

For example, running this command may produce output like the following:

C:\Windows\system32>netstat -ano 3 | findstr "SYN_SENT"

TCP 10.113.1.18:65488 10.0.26.142:6164 SYN_SENT 12348

Breaking this down:

  • 10.113.1.18:65488 → The source IP and port (VBR server attempting to connect)
  • 10.0.26.142:6164 → The destination IP and port (target WAN Accelerator)
  • SYN_SENT → The state of the connection attempt
  • 12348 → The process ID (PID) initiating the connection

The presence of SYN_SENT in this context suggests that the VBR server is trying to communicate with the WAN Accelerator but is not receiving a response—potentially indicating that the WAN Accelerator service is not running.

Confirming the Issue on the Backup Target

Once you identify a failed connection, the next step is to verify whether the WAN Accelerator service is running on the target machine. To do this:

A screenshot of a computer AI-generated content may be incorrect.

  1. Log in to the backup target server where the WAN Accelerator is configured.
  2. Open the Services console by typing services.msc in the Run dialog (Win + R).
  3. Scroll down and locate the Veeam WAN Accelerator Service service.
  4. If the service is not running, this confirms why the VBR server cannot establish a connection.

Resolving the Issue – Restarting the WAN Accelerator Service

If the VeeamWANSvc service is stopped, simply starting it should resolve the issue.

Method 1: Using the Services Console

  • Right-click on VeeamWANSvc and select Start.
  • Wait a few seconds for the service to initialize.
  • Retry the backup job.

Method 2: Using Command Prompt

For a quicker approach, open an elevated Command Prompt and run:

net start VeeamWANSvc

This starts the service immediately without requiring the GUI.

Method 3: Using PowerShell

For those who prefer automation, PowerShell can be used to check and start the service:

$service = Get-Service -Name "VeeamWANSvc"

if ($service.Status -ne "Running") {

Start-Service -Name "VeeamWANSvc"

Write-Output "Veeam WAN Accelerator service started successfully."

} else {

Write-Output "Veeam WAN Accelerator service is already running."

}

This script verifies the service status before attempting to start it, ensuring a more robust solution.

Final Checks and Job Verification

Once the WAN Accelerator service runs again, return to the VBR console and retry the failing job. If everything was set up correctly, the job should proceed without issue. To confirm proper connectivity, rerun the netstat command on the VBR server. The issue is resolved if no SYN_SENT connections related to the WAN Accelerator port appear.

Conclusion

Identifying and fixing Veeam WAN Accelerator connectivity issues doesn’t have to be a headache. By using the simple netstat command to detect blocked connections, verifying the service status on the backup target, and restarting the WAN Accelerator service, you can resolve this issue in minutes. This quick and easy method ensures that your backup jobs continue smoothly without prolonged troubleshooting.

Have you encountered similar issues with Veeam WAN Accelerators? Share your experience and any additional troubleshooting tips in the comments!

Thanks,

Dave