Network connection drops after establishing VPN (PPTP) connection on host

[h3llfir3]

Since 4.3.26 the network connection drops shortly after establishing a VPN connection (PPTP) on the host.

Guest: Windows 7 Professional, 32 Bit Host: Windows 7 Professional, 64 Bit

[Valery Ushakov]

What network attachment do you use for the guest?

Most VPN software disables all other routes, so that a host appears to be connected only to the VPN tunnel.

[h3llfir3]

Sorry for the late response, I couldn't manage to login earlier, due to the fact that I forgot my username.

I configured the network of my guest as follows:

Adapter 1

Attached to: NAT
Adapter Type: Intel Pro/1000 MT Desktop
Promiscuous Mode: Deny
[x] Cable Connected
I configured 2 Pot Forwardings for this adapter

To establish the PPTP connection from the host system I use the Windows built-in VPN tools.

Unfortunately the problem still exists in Version 4.3.28.

[Valery Ushakov]

Replying to h3llfir3:

To establish the PPTP connection from the host system I use the Windows built-in VPN tools.

So, you establish VPN connection on the host. When you say that "the network connection drops shortly after", which network connection do you mean? From guest to some remote machine on the internet? Connections to some remote machine inside the VPN?

Does "since 4.3.26" implies that 4.3.24 was ok?

I guess that you might be running into the remaining NAT link flap issue described in the later comments of 13839. Yours would be the third report and 3 out of 3 involve VPN. Please, can you provide your C:\Users\<your username>\.VirtualBox\VBoxSVC.log from a run that exhibits the problem?

There's a workaround, an extradata knob implemented in 4.3.28, see a few comments down.

[h3llfir3]

I mean the complete network connection inside the guest (indicated by a red cross in the Windows network icon at the traybar).

Yes, 4.3.24 worked well for me.

[h3llfir3]

Requested log file

[h3llfir3]

Unfortunately your suggested workaround (VBoxManage setextradata global VBoxInternal2/HostDNSSuffixesIgnore 1) does not work for me. Still having the same issue.

[Valery Ushakov]

Does the connectivity eventually comes back to be disconnected again, etc? You log only provides minute and a half worth of information. You have the set of your resolvers changed back and forth, but it's not clear what's the frequency of that.

You may want to switch to DNS proxy with

VBoxManage modifyvm "VM name" --natdnsproxy1 on

so that the change of resolvers on the host are not reported to the guest.

[h3llfir3]

That helped, thank you so much! :)