Cannot connect to Server 2019 VPN through Verizon hotspot.

Question

Hi.

I have a new Server2019 server which I have installed Remote Access / VPN on. Everything works correctly through my home network (CBTS) and through other services (Spectrum, etc).

But I have clients that need to connect to the VPN through their Verizon hotspots. When I switch my PC to my Verizon Hotspot, I get the following error trying to connect:

The VPN connection between your computer and the VPN server could not be completed. The most common cause for this failure is that at least one Internet device (for example, a firewall or a router) between your computer and the VPN server is not configured to allow Generic Routing Encapsulation (GRE) protocol packets. If the problem persists, contact your network administrator or Internet Service Provider.

I have been trying to work with Verizon 2nd level support, but have had no response.

IS there something I can check on my end to try and troubleshoot this issue?

Thanks in advance

Bob Pahls

Answer 1

The Generic Route Encapsulation (GRE) protocol is used in conjunction with PPTP. Data or payload that is going to pass through the tunnel is given a Point-to-Point Protocol (PPP) header and then placed inside a GRE packet. The GRE packet carries the data between the two tunnel endpoints. After the GRE packet has arrived at the final destination (the endpoint of the tunnel), it is discarded and the encapsulated packet is then transmitted to its final destination.

Make sure that TCP port 1723 and GRE (IP protocol 47) are open on the end points, likely your NAT router device. The device manual should have the specific details.

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Answer 2

Hi,

Thank you for posting in Q&A!

1.May I ask is your VPN server behind NAT? In that case, you might need port forwarding:
1033906

2.If your firewall didn’t whitelist your VPN when you created the secure tunnel, it might be the reason why you keep seeing VPN error 806 on Windows 10. Please try to Add an exception to the firewall and antivirus.

3.Try to Allow PPTP passthrough on your router:
Access the admin page of your router and look for PPTP and/or PPTP passthrough settings.
Enable these options for incoming and outgoing settings to ensure that your home router doesn’t block VPN traffic when using PPTP.

Hope you have a nice day : )
Gloria

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