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I can't connect to the PPTP VPN of VPN Plus Server. What can I do?

Last updated:29 Jun 2022

I can't connect to the PPTP VPN of VPN Plus Server. What can I do?

Symptoms

You set up a PPTP VPN using Synology Router's VPN Plus Server, but your client device cannot connect to it.

Resolution

Preliminary checks

  1. Go to SRM VPN Plus Server > Overview. Make sure the PPTP section is displayed.
  2. Switch to Permission > Services. Check if your SRM account has sufficient privileges to set up a PPTP VPN connection to your Synology Router.
  3. Check if you have correctly entered the SRM account credentials on your client device.1

If the issue persists, continue with the following section.

Testing steps

1. Connect via another device

Try connecting to the PPTP VPN via another device, e.g., a mobile phone. This is to check if the issue results from the client device you previously used.

2. Connect via another VPN client service

Try connecting to the PPTP VPN via another VPN client software or application. This is to check if the issue results from the VPN client service you previously adopted.

3. Connect via another network

Try connecting to the PPTP VPN from another network, e.g., the 4G network shared by a mobile phone. This is to check if the issue results from the network where your client device was previously located.

4. Connect from the VPN server's local network

Try connecting to the PPTP VPN from the local network of Synology Router by entering its private IP address.2 This is to check if the issue results from your Synology Router or its network environment. Refer to the following for details:

  • If the connection is successful, go to SRM Network Center > Security > Firewall. Check if the IP address of the previously used client device is blocked by firewall rules on your Synology Router3 (refer to this article for detailed instructions).
  • If the connection still fails, please contact Synology Technical Support for further diagnosis.

Notes:

  1. PPTP VPN is not supported on the following operating systems:
    • iOS 10 and above
    • macOS Sierra (macOS 10.12) and above
  2. The private IP address of Synology Router can be found at the paths below:
    • SRM 1.3: Go to Network Center > Local Network > Network. Select the network where PPTP VPN is set up, and click Edit > General to check the Local IP.
    • SRM 1.2: Go to Network Center > Local Network > Local IP > IP address.
  3. If there is a parent router in the local network of your Synology Router, configure the following on the parent router:
    1. Set up port forwarding rules for your Synology Router. Forward port 1723 (TCP) on the parent router to your Synology Router.
    2. Make sure no firewall rules are blocking the IP address of the previously used client device.
    3. Make sure there are no port forwarding rules configured by other devices via UPnP.
    4. Disable DMZ.
    5. Enable PPTP VPN Pass-through if it is supported by the parent router.

Further reading

Symptoms
Resolution
Preliminary checks
Testing steps
Further reading