What should I do if VPN Server doesn't work on my MERCUSYS router?
If you are using the MERCUSYS router as the VPN Server, but encounter some issues when connecting the remote clients to the server, please refer to the following cases to troubleshoot.
Case 1: Remote phone/PC fails to connect VPN Server
Case 2: Remote devices connect the VPN Server successfully but cannot access internet any more
Note: If you are unable to connect to a VPN server when trying to configure the VPN client on the MERCUSYS router, please refer to What should I do if VPN Client doesn't work on my MERCUSYS router? for troubleshooting.
Case 1: Remote phone/PC fails to connect VPN Server
Step 1. Check the router’s WAN IP address to see if it is a public IP address
1) If it is not a public IP address, it means there is another router or NAT in front of the MERCUSYS router, which blocks the VPN connection, please open a service port on the front router or NAT device for the VPN connection, and then change the private WAN IP address to your real public IP address in the .ovpn file (for OpenVPN) and .conf file (for WireGuard VPN).
For example, for OpenVPN, you could refer to Case 2 in the guide: How to use OpenVPN to access your home network through the Wi-Fi Routers.
Note: If there is no any other NAT product in front of the MERCUSYS router, it means your ISP assigns a CGNAT IP address or private IP address to you, which will cause VPN Server and port forwarding don't work, please contact your ISP to see if they could offer you a public IP address.
2) If it is a public IP address, please go to Step 2.
Note: If your WAN IP is public IP address but it is not a static IP, please set up DDNS on the MERCUSYS router, or when the public IP changes, you will not be able to connect the VPN Server again without correcting the public IP address.
Step 2. For OpenVPN Server, please try to change the type from UDP to TCP.
Step 3. Ensure the VPN Client Software on your client device is installed and running under the ADMINISTRATOR Account.
Step 4. Ensure the same time settings on your VPN client device and the MERCUSYS router.
Step 5. Try disabling the firewall and security software on your VPN Client device.
If the above steps still cannot solve the problem, please contact MERCUSYS Technical Support with the following information for further troubleshooting.
1. Model, hardware and firmware version of your MERCUSYS router, model of the VPN client device.
2. Your specific network topology and what you want to achieve via VPN
3. The current problem phenomenon.
4. The .ovpn file for OpenVPN or .conf file for WireGuard VPN, and screenshots of all VPN Settings
5. Log file of the VPN client if you have.
Case 2: Remote devices connect the VPN Server successfully but cannot access internet any more
For this issue, please contact MERCUSYS Technical Support with the following information:
1. Model, hardware and firmware version of your MERCUSYS router, model of the VPN client device.
2. The .ovpn file for OpenVPN or .conf file for WireGuard VPN, and screenshots of all VPN Settings on the router.
3. The current problem phenomenon.
Case 3: Remote devices connect the VPN Server successfully but cannot access local resource of the VPN Server
1. Try disabling the firewall on the client device temporarily to see if that resolves the issue.
For example, Windows PC typically blocks remote traffic from VPN client since its IP address is from a different subnet. You can create a new inbound rule to allow traffic from the specific IP address of the VPN client. Please refer to Create an Inbound Port Rule (Windows)
2. Some devices may not be compatible with VPN networks or may require special configuration. You may try port forwarding as an alternative solution. Please refer to Port forwarding: how to set up virtual server on MERCUSYS Wi-Fi router?.
It’s also recommended to contact the support team of that device for assistance.
Note: When connected via VPN, devices on your local network (such as computers, printers, or NAS) may not appear under “Network” in File Explorer. This is expected behavior since network discovery traffic cannot pass through the VPN tunnel. You can still access them directly by using their IP addresses.