my Problem - I can't connect with my Windows 10 to my work VPN via SonicWall Mobile Connect.

what do I know - If I use my mobile hot spot it works but not when I use my Cable connection (over ISP) it is not working. I get timeouts and I cant put in my credentials.

  • I disabled all firewalls (Router, Windows), windows defender and so on
  • IPv4 and IPv6 is activated

what do i think the problem is

It looks like the ISP (Unitymedia GER) uses DS-Lite so my IPv4-Address is not reachable for my companys VPN. I assume that this causes the problem. Unfortunatly my company doesn't use IPv6 yet and I dont know if I can force them to do so.

I read about the problem here and here. Both suggest to use a Tunnel service like http://www.feste-ip.net/ or https://tunnelbroker.net/.

But I don't understand how this could help me since every article is about if they have some service running and want to reach them from the internet. My thought was (and maybe this is why I fail) that I want to have a kind of translator which routes me to my destination and back.

  1. My client pc calls via IPv6 some middle man address
  2. The address forwards my request to my companys address via IPv4
  3. Company sends requests to the middle man who sends it back to me via IPv6 (and so on)

I'm happy about every hint. If you need more details please let me know.

  • 1
    Unfortunatly my company doesn't use IPv6 yet and I dont know if I can force them to do so. Ask. Native IPv6 will be a better experience than the combination of NAT and encapsulation that is not giving you working IPv4. May 29, 2019 at 16:36
  • @JohnMahowald thank you and I've asked them. But if not how could I solve the problem? I read about NAT64 but my first test failed, is this the right way or is there any other way or tutorial you can suggest? May 29, 2019 at 16:44
  • Your VPN connection ought to work fine over DS-Lite even if your company does not yet have an IPv6 endpoint for the VPN. I would have a chat with your IT department about this. There might be something else going on. May 29, 2019 at 16:52
  • @MichaelHampton do you might know what it could be? We tried to solve it. What confuses me is the fact it works with my mobile hotspot. May 29, 2019 at 16:55
  • 2
    Your IT can rule out problems with the VPN server end, so then you can blame the ISP - because at this point it probably is their fault. May 29, 2019 at 16:57

1 Answer 1


My ISP (Unitymedia) just confirmed it. It is not possible with my internet setup to connect to a IPv4 VPN Server. The setting Dual Stack Lite, or short DS-Lite, needs to be activated.

In my case I had to upgrade my account from 50mbit to 100mbit as well as adding upload boost option which gives me 200mbit up and 40mbit down. The Dual Stack Lite option was for free.

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