Application Guard when on VPN fails with "You're not connected"

Question

Application Guard when on VPN fails with "You're not connected"

ComputerHabit 1,036

I have Application Guard running. It works fine when not connected to VPN.
When connected to VPN it fails with "You're not connected".

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How do I configure Application Guard to work when I'm on VPN?

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Answer 1

Wenying Lu-MSFT 2,090 Microsoft External Staff

Hi @ComputerHabit ,

Are you running Application Guard in Standalone mode? First, you can try to check if you have met all the System requirements. Second, you can refer to this FAQ to see if it can fix the issue.

If issue persists, it's may be related with your local environment and need complex troubleshooting, I suggest that you can open an assisted support ticket so that you can get more help.
Thanks for your understanding.

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Regards,

Wenying Lu

ComputerHabit 1,036 Reputation points

2023-10-30T11:26:25.8333333+00:00

It is related to having the VPN turned on. :)

There are no details on Microsofts website on how to deal with this.
Wenying Lu-MSFT 2,090 Reputation points Microsoft External Staff

2023-10-31T06:43:16.87+00:00
Hi @ComputerHabit ,

Thanks for your reply.

You could try to following methods from Microsoft Defender Application Guard FAQ：

1.How do I configure Microsoft Defender Application Guard to work with my network proxy (IP-Literal Addresses)?

Application Guard requires proxies to have a symbolic name, not just an IP address. IP-Literal proxy settings such as 192.168.1.4:81 can be annotated as itproxy:81 or using a record such as P19216810010 for a proxy with an IP address of 192.168.100.10. This annotation applies to Windows 10 Enterprise edition, version 1709 or higher. These annotations would be for the proxy policies under Network Isolation in Group Policy or Intune.

2.I'm encountering TCP fragmentation issues, and can't enable my VPN connection. How do I fix this issue?

WinNAT drops ICMP/UDP messages with packets greater than MTU when using Default Switch or Docker NAT network. Support for this solution has been added in KB4571744. To fix the issue, install the update and enable the fix by following these steps:

Ensure that the FragmentAware DWORD is set to 1 in this registry setting: \Registry\Machine\SYSTEM\CurrentControlSet\Services\Winnat.

Reboot the device.

Please let us know if you have any updates.

Regards,

Wenying Lu

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Application Guard when on VPN fails with "You're not connected"

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