VPN Not Connecting — Diagnose and Fix Any VPN

Universal VPN Troubleshooting Framework

VPN failures fall into three categories: authentication failures (wrong credentials), network blocks (ISP/firewall blocking VPN protocols), and server-side issues.

Fix 1: Change VPN Server

The fastest first step: switch to a different server in the same country. Server-side issues are temporary and server-specific.

Fix 2: Change VPN Protocol

In VPN app settings, switch: WireGuard → OpenVPN → IKEv2. Some ISPs and hotel/corporate networks block specific protocols. OpenVPN TCP 443 is almost never blocked since it looks like HTTPS traffic.

Fix 3: Disable Firewall/Antivirus Temporarily

Windows Defender and third-party antivirus can block VPN tunnel establishment. If VPN connects with them disabled, add a firewall exception for your VPN application.

Fix 4: Flush DNS and Reset Winsock (Windows)

Command Prompt as Admin:
netsh winsock reset
netsh int ip reset
ipconfig /flushdns
Restart your computer.

Fix 5: Reinstall the VPN Client

Completely uninstall (including TAP drivers on Windows) → Restart → Download latest client from provider’s official website → Reinstall. Corrupt TAP/TUN driver installs prevent all VPN protocols from working.