Slow Connection with Windows Print Servers

“Help! I’m a print server administrator, and I’ve noticed that not only are documents slow to print, but it’s also really slow to connect to a shared Windows print queue on our server. Why does this happen and how do we fix it?”

Users or administrators may experience noticeable delays (often timing out or hanging for around 45 seconds) in the following scenarios:

• Connecting to or mapping a shared print queue on a Windows Print Server.
• Opening the print dialogue box or submitting a print job from a client workstation.
• When PaperCut redirects a print job from one Windows print server to another (known as cross-server redirection).

Note: This issue can happen whether or not PaperCut is installed and can affect any Windows print environment.

This issue is commonly caused by restricted Windows Print Spooling Ports across your network.

Modern Windows operating systems rely on Remote Procedure Call (RPC) for print spooler communication. RPC uses TCP 135 (Endpoint Mapper) and a dynamic port range (ports 49152 through 65535) to establish these connections.

When a network firewall, endpoint protection, or router blocks these dynamic ports, the client attempts to establish an RPC connection over the dynamic port range. If this connection cannot be established, it will wait for a timeout (typically around 45 seconds), after which Windows falls back to legacy SMB-based communication over TCP ports 445 and 139.

This fallback introduces the delay.

How to Verify the Issue

You can confirm if your print spooler is being forced to use the legacy fallback ports by using the netstat command directly on your Print Server.

1. Log in to your Windows Print Server.
2. Click the Start menu, type cmd, right-click Command Prompt, and select Run as administrator.
3. Run the following command exactly as written: netstat -b -n
4. Review the output for the spoolsv.exe process.

Interpreting the Results:

• Healthy Environment: If spoolsv.exe is utilising randomly assigned ports within the 49152–65535 range, this indicates dynamic RPC ports are in use.
• Potentially Blocked Environment: If you only observe connections over TCP ports 445 and 139 during client connection attempts, and do not see dynamic high ports (49152–65535) in use, this may indicate that RPC dynamic ports are being blocked on the network.

What can I do about it?

To resolve these slow connections, you must ensure required RPC ports are allowed to communicate freely between the client workstations and the print server.

1. Ensure that the following ports are allowed between client workstations and the print server:

• TCP 135 (RPC Endpoint Mapper)

• TCP 49152–65535 (dynamic RPC port range).

  This includes:

• Windows Defender Firewall (on both the server and client sides).

• Network hardware appliances (e.g., routers, switches handling inter-VLAN routing).

• Third-party endpoint security or antivirus software.

2. Once your firewall rules have been updated, you may need to restart the Windows Print Spooler service for the network changes to take effect.

• Using the GUI:
  1. Open the Run dialogue (Windows Key + R), type services.msc, and press Enter.
  2. Locate Print Spooler in the list.
  3. Right-click it and select Restart.
• Using PowerShell:
  1. Open PowerShell as an Administrator.
  2. Run the following command: Restart-Service -Name Spooler -Force

Check out our comprehensiveFirewall Ports article for a complete list of ports used by the Windows Printing system and PaperCut.

Still experiencing delays after opening these ports? Review our primary Troubleshooting slow printing guide for additional steps.