Error Code error-ipsec-auth-firewall-drop — Windows 11

Postup řešení

1. 1 Press Windows key + R, type 'wf.msc' and press Enter. This opens Windows Firewall with Advanced Security. In the left pane, click 'Connection Security Rules'. Look for any rules that are blocking IPsec traffic. If you see a rule with a red icon, it might be blocking. Right-click it and select 'Disable Rule' to temporarily disable it, then try your VPN connection again. If it works, you've found the culprit.
2. 2 If disabling a rule works, you need to modify it instead of leaving it disabled. Right-click the rule and select 'Properties'. Go to the 'Authentication' tab and ensure that 'Require authentication' is selected, and that the authentication method matches your VPN's requirements (e.g., 'Computer and User (Kerberos V5)'). Also check the 'Protocol and Ports' tab to ensure it's not overly restrictive.
3. 3 Sometimes third-party antivirus software has its own firewall that interferes. Temporarily disable the third-party firewall (not Windows Defender) from its settings, then try the VPN. If it works, you need to configure the third-party firewall to allow IPsec traffic. Add an exception for your VPN client and for IPsec ports (UDP 500 and 4500).
4. 4 If the error persists, reset Windows Firewall to default. Press Windows key + X, select 'Windows Terminal (Admin)', and type 'netsh advfirewall reset' and press Enter. This restores all firewall rules to their default state. Note that this will remove any custom rules you've created, so back them up first. After reset, reboot and try the VPN again.
5. 5 If you're still stuck, check the Windows Event Viewer for more details. Press Windows key + X, select 'Event Viewer', go to 'Windows Logs' > 'Security'. Look for events with ID 5152 (Windows Filtering Platform blocked a connection). The event details will show which program or rule caused the drop. Use that information to adjust the specific rule.