@Legowski 

Hi, welcome to our community.

Here are some suggestions for your reference:

1. Verify VPN Configuration
Check Port Forwarding: Ensure that port forwarding is correctly set up in the AirVPN client. Make sure the local port (32400) is forwarded to the correct external port.
Use the Correct External Address: When configuring Plex, ensure you're using the public IP address provided by AirVPN, not your local IP.
2. Update Plex Settings
Manually Specify Ports: In the Plex settings, go to Settings > Remote Access and specify the external port you set up in the AirVPN client.
Enable Remote Access: Make sure the "Enable Remote Access" option is checked.
3. Firewall Settings
Windows Firewall: Ensure that the Windows Firewall allows traffic on the Plex port (32400). You may need to create a new inbound rule.
VPN Firewall: Check if AirVPN has any firewall settings that might be blocking the Plex traffic.
4. Test Connectivity
Use Port Checking Tools: Use online port checking tools to see if the port is accessible from outside your network when connected to the VPN.
Check VPN Logs: Review AirVPN logs for any errors or warnings related to port forwarding.
5. Restart Services
Restart both the Plex server and the AirVPN client to apply any changes made.
6. Alternative Solutions
Try Different Ports: If issues persist, try using a different port for Plex and update both the VPN and Plex settings.
Contact Support: If none of the above steps work, consider reaching out to AirVPN or Plex support for further assistance.
Additional Tips
Make sure your Plex server is updated to the latest version. Keep your VPN client updated as well.

Thank you and best regards.