Can't open VPN with mobile hotspot, error 806 - Windows 7

[Frick]

Hey all.

So I have a VPN access to a network. but it doesn't work when I use my phone as a hotspot, but only on a specific machine, a Fujitsu T730 (Atheros AR2987). It runs a fully updated Windows 7 Pro. On a "normal" router it works just fine. The hotspot works on other machines, it's only on this one it doesn't work. I've tried Android and iOS, and the IP ranges are not conflicting with each other.

The error I get is 806, saying this:

Error Description: 806: 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.

Possible Cause: PPTP uses GRE (Generic Route Encapsulation) protocol to encapsulate the VPN payload in a secure manner.This error generally comes when some firewall in path between client and server blocks GRE Protocol (i.e. IP protocol number 47).

Possible Solution: Allow both outgoing and incoming Protocol 47 (GRE) on any in between firewalls. If that is not possible, deploy SSTP based VPN tunnel on both VPN server and VPN client – that allows VPN connection across firewalls, web proxies and NAT.

The machine is clean, we only use it for one thing and that is troubleshooting/installing measuring equipment in electrical installations.

I've never used VPN's before, I have no idea where to even begin. It can't be firewalls/routers/switches or something because it works with other machines. Or at least I am assuming this. So any ideas are welcome!

EDIT:

Uhh, the problem might be some software strangeness, as I know have connection problems all over the place. Currently I'm connected like this: property router -> managed switch -> dumb switch -> dumb switch (the last two being my workplace network) and it intermittently has no internet connection. The same goes for WiFi, which up to this point worked just fine. It connects to the network, but no internet. Everything else connected to the same network has internet access.

 

[Frick]

Network problems aside (which doesn't really apply because I'm on the mobile hotspot), I honestly have no idea where to even begin. Drivers are up to date, I've checked with the carrier and they allow that kind of traffic, settings are as they should, no malware anywhere.

 

[Rhyseh]

Windows firewall disabled?

 

[Kursah]

I would wipe out the VPN settings, and rebuild them, and I would get another known good PC that does work alongside that one using the same connection. Check each page, especially the authentication settings... even with the low grade and almost unsecure PPTP VPN protocol it is usually security or authentication settings that get screwed up.

Things to check: http://www.howtonetworking.com/vpnissues/error806.htm

As suggested prior, check Windows Firewall...but odds are that you won't find much there it does happen from time-to-time.

In my experience it is either a filtered/firewalled connection blocking the tunnel (like a guest network @ a hotel), or settings on the host (your PC). Check against another workstation and verify all security settings are exactly matched. Are you using the same credentials between all workstations? Are you authenticating against AD? If you're using an AD account that doesn't have the correct memberships and security permissions, it won't connect as well..but iirc that's a different error code.

Are you using the same Internet connection (WiFi/Ethernet) between machines that do/don't work?

 

[Solaris17]

it might be your carrier. I know some ISPs block VPN on consumer networks so you have to pay for business plans. Your cell carrier may do just this to prevent exactly what you are doing.

EDIT::nvm learned how to read.

 

[Frick]

I would wipe out the VPN settings, and rebuild them, and I would get another known good PC that does work alongside that one using the same connection. Check each page, especially the authentication settings... even with the low grade and almost unsecure PPTP VPN protocol it is usually security or authentication settings that get screwed up.

Things to check: http://www.howtonetworking.com/vpnissues/error806.htm

As suggested prior, check Windows Firewall...but odds are that you won't find much there it does happen from time-to-time.

In my experience it is either a filtered/firewalled connection blocking the tunnel (like a guest network @ a hotel), or settings on the host (your PC). Check against another workstation and verify all security settings are exactly matched. Are you using the same credentials between all workstations? Are you authenticating against AD? If you're using an AD account that doesn't have the correct memberships and security permissions, it won't connect as well..but iirc that's a different error code.

Are you using the same Internet connection (WiFi/Ethernet) between machines that do/don't work?

How it looks so far, it's something with my phone I think.

• Disabled firewall - no change
• It works on two other machines (HP Elitebooks 8560W with Intel Advanced-n 6205), it works on those machines
• It works with other the DSL connection we have at the office, both wired and wifi
• It works when using my coworkers iPhones as hotspots. One of them consistently (4S with 8.1.3) and one of them intermittently (6 Plus with 9.0). The 6 Plus has the exact same subscription as I have, the 4S has a different carrier but that doesn't matter much because they use the same network
• All settings are identical
• Scanned the machine for malware/virus - nothing found
• Disabled all other network interfaces - no change
• Deleted the connection and set it up again - no change
• Manually opened port 1723 in the firewall with the GRE protocoll - no change

Now, our internal IP adress can't be set to 192.168.1.x, it conflicts with the VPN thing. iOS slobs out 172.20.10.x, Android 192.168.42.x, so it shouldn't be that.

EDIT: My phone (Sony Z3, android 5.1.1) needs a 6 number pin-lock to use VPN's, so for the lulz I enabled the VPN function on the phone, but still no go.

 

[Kursah]

The IP address depending on how your VPN setup could be correct, as there is usually a different subnet scope/range for VPN clients. While some networks do forward to the company network for DHCP as well, that is usually handled at the border of the network where the VPN tunnel is hosted server-wise and is usually on a different subnet. Interesting iOS and Android have different IP addresses though. Once clients have an IP, it is up to setting up routing in the VPN server to forward to the internal subnet of your network so you can gain access.

Could be your phone, are you on the same phone service as the rest of the folks? I know I had issues using a VPN through my Straight Talk AT&T connection up until early this year. At this point it is all pointing to your phone connection. Funny that the 6 Plus is intermittent, makes me wonder if it can't handle the connection or is filtering it.

The VPN function on your phone I believe is to just connect your phone to a VPN tunnel, so ya that shouldn't have done anything. I have no experience with Sony Zx series phones and VPN tunnels. But as I said before, PPTP is about as basic as you can get, with minimal to no protection, so if you can't connect using your phone or its service, that's likely the culprit.