How to Fix VPN Not Connecting on Windows
VPN won't connect or keeps disconnecting on Windows? Fix VPN connection failures including error 800, 789, and L2TP/IPsec issues.
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Main Troubleshooting Guide
How to Fix No Internet Connection →Complete symptoms, causes, and step-by-step solutions
Symptoms
You might be experiencing this problem if you notice:
- •VPN connection attempt times out
- •Error 800: "Unable to establish the VPN connection"
- •Error 789: L2TP connection attempt failed
- •VPN connects but no internet access
- •VPN disconnects after a few minutes
- •Built-in Windows VPN not showing in network list
Common Causes
- ⚠Firewall blocking VPN ports (500, 4500, 1723)
- ⚠L2TP/IPsec registry keys missing
- ⚠IKEv2 or SSTP certificate issues
- ⚠VPN adapter driver corrupted
- ⚠NAT traversal not configured
- ⚠Conflicting VPN clients installed
Solutions
Solution 1: Fix L2TP/IPsec Registry Setting
- 1Press Windows + R, type regedit
- 2Navigate to HKLM\SYSTEM\CurrentControlSet\Services\PolicyAgent
- 3Right-click > New > DWORD (32-bit) Value
- 4Name it "AssumeUDPEncapsulationContextOnSendRule"
- 5Set value to 2
- 6Restart your computer and try connecting
Solution 2: Restart VPN Services
- 1Press Windows + R, type services.msc
- 2Find and restart these services:
- 3- IKE and AuthIP IPsec Keying Modules
- 4- IPsec Policy Agent
- 5- Remote Access Connection Manager
- 6Set all three to Automatic startup
- 7Try your VPN connection again
Solution 3: Reinstall VPN Adapter
- 1Open Device Manager
- 2Click View > Show hidden devices
- 3Expand "Network adapters"
- 4Find WAN Miniport entries (IKEv2, L2TP, PPTP, SSTP)
- 5Right-click each > Uninstall device
- 6Restart your computer — Windows will recreate them
- 7Reconfigure your VPN connection
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