Windows ERROR_81 can be frustrating. It typically indicates a network connectivity issue, often related to problems with VPN access or domain authentication. If you’re encountering this error, don’t worry — this comprehensive guide will walk you through the troubleshooting process, step by step.
What is Windows ERROR_81?
Before diving into the fix, understanding the error helps. ERROR_81 usually manifests as:
- “ERROR 81: The remote access connections are busy or unavailable.”
- Issues connecting to a VPN or domain.
- Network-related failures when accessing shared resources.
This error points to a problem with network connectivity, permissions, or misconfigured settings.
Why Does ERROR_81 Appear?
Common causes include:
- Network adapters misconfiguration.
- VPN connection conflicts.
- Firewall or antivirus software blocking access.
- Incorrect DNS or routing settings.
- Interrupted or busy remote access server.
How to Fix Windows ERROR_81: Step-by-Step
Step 1: Restart Your Computer and Network Devices
It sounds simple, but many network problems resolve after a restart.
- Restart your PC: This refreshes system services.
- Restart your modem/router: Unplug for 30 seconds, then plug back in.
- Restart VPN client and try connecting again.
Step 2: Check Your Network Connection
Make sure your PC is connected to the internet without issues:
- Click the network icon on your taskbar.
- Open Network & Internet settings.
- Run Network Troubleshooter to detect and fix potential problems.
- Ensure you’re not connected to a restricted or public Wi-Fi that blocks VPN.
Step 3: Disable Conflicting VPN or Network Software
If you use multiple VPNs or network utilities, conflicts can cause ERROR_81.
- Open Control Panel > Programs and Features.
- Temporarily uninstall or disable secondary VPN clients.
- Make sure only the VPN you intend to use is active.
- Also, briefly disable third-party firewall/antivirus for testing.
Step 4: Reset Network Settings
Resetting network configurations can clear corrupt settings:
- Open Command Prompt as Administrator:
- Press
Windows + S, typecmd, right-click Command Prompt, select “Run as administrator.”
- Press
-
Execute these commands one by one:
netsh winsock reset
netsh int ip reset
ipconfig /release
ipconfig /renew
ipconfig /flushdns - Restart your PC after running these commands.
Step 5: Verify VPN Configuration
If you’re connecting via VPN, errors might stem from incorrect settings:
- Check VPN server address and your credentials.
- Ensure VPN protocols (PPTP, L2TP, SSTP…) are correctly set.
- Refer to your VPN provider or IT team for correct settings.
- If possible, try connecting from a different device/network.
Step 6: Check Windows Firewall and Security Settings
Firewalls often block remote access ports needed by VPN.
- Open Windows Defender Firewall.
- Click Allow an app or feature through Windows Defender Firewall.
- Ensure your VPN app is allowed on both Private and Public networks.
- Temporarily disable Windows Firewall and test the connection. If it fixes the issue, adjust firewall rules properly.
Step 7: Update Network Adapter Drivers
Outdated drivers cause compatibility problems:
- Press
Windows + X, select Device Manager. - Expand Network adapters.
- Right-click your adapter, select Update driver.
- Choose Search automatically for updated driver software.
- Restart your PC after updating.
Step 8: Review Domain or Workgroup Settings (If Applicable)
For domain-joined PCs, ERROR_81 could indicate domain trust issues.
- Ensure your PC is connected to the corporate network.
- Confirm your domain account credentials are valid.
- Contact your domain administrator for help if you can’t authenticate.
Additional Tips
- Test with another network: Try a mobile hotspot or different internet.
- Use built-in Windows VPN: If your third-party VPN fails consistently.
- Review Event Viewer logs: For detailed error messages. Press
Windows + X> Event Viewer > Windows Logs > System/Application.
Conclusion
Windows ERROR_81 can feel like a big hurdle, but with these methodical steps, you’ll most likely find the culprit and fix it. Network errors are often caused by misconfigurations or conflicts — so checking connection status, resetting network settings, and verifying VPN/firewall settings are key.
Need More Help?
If you continue facing ERROR_81 after these steps:
- Contact your VPN service support.
- Reach out to your corporate IT department.
- Visit Microsoft’s support forums for similar cases.
Hopefully, this guide helped get you back online smoothly! Stay patient, follow each step, and you’ll beat ERROR_81 soon.
