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When my Windows 10 is connected to PPTP VPN connection, I can still use the local IP address of the device that DHCP gave it, to connect to my Windows 10 from Android RD client app. this shouldn't happen as I haven't "unchecked" the box that this answer is referring to.

enter image description here

so why is that? is this because of a configuration on the server side? or the IP table or DNS cache on Windows 10 still knows/remembers how to route local traffic? I really want to know the reason.

harrymc
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Sam
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  • Which VPN is that? None of the VPNs I use has this exact dialog. Hpw do you get to this dialog? – harrymc Nov 29 '20 at 18:51
  • @harrymc normal PPTP VPN, with server address, username and password. I created a VPN connection through Windows settings. don't mind the black background, i'm using Windows insider Dev build, it's a known issue. I got the dialouge by following the answer in that question I linked above. – Sam Nov 29 '20 at 18:56
  • One should expect problems in an insider Dev build. You should signal this to Microsoft. If this is a known issue, then just wait for a later release. – harrymc Nov 29 '20 at 19:00
  • The black background is the known issue, not the VPN connection or anything related to that. I can reproduce this on a stable build too and I have reproduced this before on stable builds. – Sam Nov 29 '20 at 19:02

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The option you have set relates to your own connections to the outside world, meaning connections from your computer to the outside will go by default through the VPN.

This sets the default gateway address (0.0.0.0) routing rule to point to the VPN.

It does not affect incoming connections. Blocking these connections is best done in the Windows Firewall.

harrymc
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  • Thank you, now I understand why it happens. so once an incoming connection to my computer (while it's connected to VPN) is established for the first time, my computer knows how to communicate back, i.e. make an outgoing connection, to respond. because the remote desktop operates seamlessly and correctly. can you please explain why this happens? I believe it's related to the features of networking. because according to your answer, if it was the other way around, if my computer connected to VPN, tried to use local IP to connect to another local device for RDP, it would fail. – Sam Nov 29 '20 at 20:48
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    The incoming connection establishes a means for communicating back and forth, for as long as it stays connected. The computer doesn't need to connect back for returning the answer, as the connection is already established. – harrymc Nov 29 '20 at 20:53