Windows 7 PPTP VPN stopped working

[Val Killmore]

Hi there.

I have been at this for about two days, researching and such. And my search results have come up short, so I thought I might ask for help.
I was able to access my LAN via PPTP VPN up until the other day and I can't figure out what has changed.

As far as my VPN settings on my phone, I know they have not changed. My username, and password are the same ones I use to login to my PC and I know them off by heart.

I have eliminated the firewall as a problem by completely disabling it.
I made sure VPN clients are allowed to access my LAN, and to use DHCP to assign users an ip address, and that my phone's MAC address is allowed access to my LAN thru my router.
I have tried from my mobile data network, and from various other wifi spots. Same errors no matter what I do.
I have verified that the query is making it to my PC and past my router by seeing the "RAS (Dial in) Interface" pop up in Network and Sharing Center shortly after selecting the VPN on my phone.

But I then receive an error on my phone stating "the server hung up. the username and password are incorrect".
Now I know this is not true, and I have verified multiple times that both are indeed correct, and they do match what they have always been.
I have even delted the Incoming Connections and then set up a new one with the proper, verified credentials as always, but no luck.

This used to be a very simple one-click, type password then in.......process.

I do, however, see in Network and Sharing page that the access type for the RAS (dial in) Interface is showing as : No Network Access

I have no idea where to go from here and everything I find online seems outdated and mostly XP advice.

Any advice, or suggestions for a route to take would be much appreciated. Thanks in advance.

 

[ChatGPT]

It sounds like you've done a thorough job troubleshooting your PPTP VPN connectivity issue. Since you've already checked various settings and configurations, let's explore a few additional steps you can take to tackle this problem:

Suggestions for Troubleshooting PPTP VPN Issue:​

1. Check Authentication Protocol: Ensure that the authentication protocol (MS-CHAP v2 or EAP) used by your PPTP connection is correctly configured on both the VPN server and your phone.
2. Update VPN Server Software: Check for any updates to your VPN server software or firmware. Sometimes outdated software can lead to compatibility issues.
3. Check Event Viewer: Look into the Event Viewer on your VPN server for any error logs related to the failed connection attempts. This may provide more specific information on what went wrong.
4. Verify VPN Ports: Confirm that the necessary ports (TCP 1723 and Protocol number 47 for GRE) are open and forwarded to the VPN server on your router.
5. Test Connection with L2TP/IPSec: Consider trying to connect using L2TP/IPSec as an alternative VPN protocol to see if the issue is specific to PPTP.
6. Mobile Data Connection: Try connecting to the VPN using a different mobile device (if available) to isolate whether the issue is device-specific.
7. Temporary Disconnection: Sometimes restarting both the phone and the VPN server temporarily can resolve connectivity issues.
8. Security Software: If you have any security software installed on your phone that might interfere with VPN connections, try temporarily disabling it for troubleshooting.

   Route to Take:​

9. Event Viewer Analysis: Check the Event Viewer on your VPN server for any relevant error messages that may shed light on the connection issue.
10. Protocol Testing: Test the connection using L2TP/IPSec to see if you can establish a successful VPN connection.
11. Verify Port Forwarding: Double-check that the necessary ports are correctly forwarded to your VPN server. By following these steps, you should be able to gather more information about the issue and potentially resolve it. If you encounter any specific error messages or logs, feel free to share them for further assistance. Good luck with your troubleshooting!