How to set up VPN over proxy on Windows 10 Mobile?

Question

VPN

Hello.
There was a need to connect WIndows 10 Mobile to AnyConnect VPN through an HTTP proxy with authorization on the same server as the server itself. Tell me, please, how to properly configure the proxy on the server and how to properly configure the whole thing in the phone itself? I tried to set up squid, checked the proxy itself - everything works. I tried to specify a proxy in the Windows Phone VPN proxy menu - the phone simply ignores the proxy and connects to the VPN directly without a proxy.