Host appears to be up, but had a network related error (-255)


Host appears to be up, but had a network related error (-255)


This error is usually related to problems being experienced with the Windows agent.  Use the following steps to troubleshoot:



  1. Ensure your Unitrends appliance is on the latest version. If it is not, restart the Unitrends system, then update the system to the latest version. If you wish to reboot the system after the update, please wait at least 30 minutes to ensure all update related processes have completed.
  2. Ensure all computers with a Client Agent installed are on the latest Agent version. This can be found after the update of the Unitrends system, in the Shared Directory windows_agents.
  3. Verify that if you have a local firewall or Anti-virus running on the client to allow firewall to allow traffic on ports 1743 through 1745.
  • With the Anti-virus, make sure that you add exceptions or permissions for the BP Agent service to be able to run. Also, add the C:\PCBP directory to the Exclusion/Allow.
  • First verify the IP address of the Client is correctly identified in the Unitrends system.
  • Verify that all VSS writers are "Stable" with no errors. (See KB 4085)
  • Restart the BP Agent Service.
  1. If the issue continues,
  • In the PCBP folder on the client, scroll down to the Master.ini file and open the file. Change the Data port from 1745 to 1744, stop and restart bpagent service in Services, and run new Master/Full to see if the agent will talk to the UEB/DPU.
  • Example of Data port in Master.ini below:Example:
; Debugging levels for the processes on a scale from 0 - 5
data=1745 <-- Change to 1744
  • Once this has been saved, restart the BP Agent. Then, run a new Master.
  1. If changing the port, and running a new Master/Full backup doesn't work, follow the steps below:
  • Uninstall the agent and reinstall the agent on the client.
  • Go back to the User Interface (GUI) and go into Settings>Clients, Networks, and Notifications>Clients, then click on the client and resave at the bottom.
  • Run a new Master/Full. If this still doesn't transfer data, then continue with the next steps.
  • Remote out to the Client and open a command prompt and run as Administrator.
  • From the Command Prompt, type the following command string: netstat -a -n -o | find ":1745" or netstat -a -n -o | find ":1744"
  • This command will return the following example which should show if the client is holding the ports 1745 or 1744.

Example Data Port 1745:

Active Connections
Proto     Local Address              Foreign Address                     State
TCP       (Local Client):1745      (DPU/UEB):1743<--Static       LISTENING

Example Data Port 1744:
Active Connections
Proto     Local Address              Foreign Address                     State
TCP       (Local Client):1744      (DPU/UEB):5321<--Dynamic   LISTENING

  • If the above shows that State is stuck in a TIME_WAIT status, then you would need to restart the bpagent in Services or reboot the client to release the thread.
  • Also bring up Task Manager and make sure that there aren't any extra WBPS.exe processes running.
  • If the changing of the above doesn't fix the issue, then call into support or come into support chat for assistance


Windows 2003 Issues: 

After an upgrade of the Windows 2003 32-bit agent, the backup system can no longer communicate with the agent and the error below is presented when a backup is attempted.

Task failed: Host appears to be up, but had a network related error (-255) Host appears to be up, but had a network related erorr (-255)

Running the command netstat –abn | find “:1743” produces the following output:


Resolution for Windows 2003 issues:

This may be an indication that the agent did not get cleanly installed.  Use these steps to uninstall and reinstall the agent software.

  1. Uninstall the current installation of the Unitrends agent software
  2. Manually remove (or rename) the PCBP directory located at the root of the C Drive (or the location you chose during installation).
  3. Reboot the Windows server.
  4. Download the Unitrends Client Agent installer from the Unitrends website.
  5. Install the Unitrends agent software (this must be done using Administrative privileges).
  6. For Windows 2003/XP and older systems, also install the Unitrends Bare Metal Agent as you will need to create a bare metal media which is required to load the bare metal backup during a restore.


First, consider elevating the debugging log levels to 3 for the WBPS and WBPR in the file C:\PCBP\MASTER.INI under [debugging], then restart the BP Agent Windows Service.


After the file has been modified and saved, restart the BP Agent service.

This needs to be performed after you have installed the latest Client Agent (after step 2 in the Resolution section) and before you begin running the new backups.

If after following the steps in the Resolution section, the issue is yet to be resolved, please submit the logs to

The logs must be compressed into a ZIP file with the format of Case Number_Client Name. (Example: The logs we need are in C:\PCBP\CATALOG.DIR and in C:\PCBP\LOGS.DIR

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