Hello there,
You can disable your proxy and return to the default settings as one of the simplest fixes. To accomplish this, adhere to the guidelines below:
Windows Key+S on your keyboard.
Enter after typing "control panel" without any quotes.
Then select Network and Internet.
Choosing Internet Options
Click LAN settings after switching to the Connections tab.
Check the box next to "Use a proxy server for your LAN" and deselect it.
The option next to "Automatically detect settings" should be checked.
To save your changes, click OK.
Similar discussion here https://learn.microsoft.com/en-us/answers/questions/1132785/windows-defender-application-guard-doesnt-work-pro
Hope this resolves your Query !!
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