NDIS6 driver: route set, but interface not used

[egroeper]

I'm testing with Virtualbox Windows Machines Win 7 and Win 8 64 Bit (and one physical machine Win 8.1 32 Bit).
On all of this machines with NDIS6 OpenVPN tunnel is successfully established and routes get set, but it seems like the interface doesn't get used.

tracert shows, that traffic passes the physical interface directly:

C:\Users\Administrator>tracert 8.8.8.8

Routenverfolgung zu google-public-dns-a.google.com [8.8.8.8] über maximal 30 Abs
chnitte:

  1    <1 ms    <1 ms    <1 ms  hypervisor [10.0.2.2]
  2     5 ms    <1 ms    <1 ms  gateway [141.20.1.1]
...

When running tracert packet counter (packets sent) on both, physical interface and tap interface increase. It seems like tap interface is tried and then the physical interface is used.

IPv4-Routentabelle
===========================================================================
Aktive Routen:
     Netzwerkziel    Netzwerkmaske          Gateway    Schnittstelle Metrik
          0.0.0.0          0.0.0.0         10.0.2.2        10.0.2.15     10
          0.0.0.0        128.0.0.0     141.20.212.1   141.20.212.118     20
         10.0.2.0    255.255.255.0   Auf Verbindung         10.0.2.15    266
        10.0.2.15  255.255.255.255   Auf Verbindung         10.0.2.15    266
       10.0.2.255  255.255.255.255   Auf Verbindung         10.0.2.15    266
        127.0.0.0        255.0.0.0   Auf Verbindung         127.0.0.1    306
        127.0.0.1  255.255.255.255   Auf Verbindung         127.0.0.1    306
  127.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
        128.0.0.0        128.0.0.0     141.20.212.1   141.20.212.118     20
      141.20.16.0  255.255.255.192     141.20.212.1   141.20.212.118     20
     141.20.212.0    255.255.255.0   Auf Verbindung    141.20.212.118    276
   141.20.212.118  255.255.255.255   Auf Verbindung    141.20.212.118    276
   141.20.212.255  255.255.255.255   Auf Verbindung    141.20.212.118    276
   193.174.167.74  255.255.255.255         10.0.2.2        10.0.2.15     10
        224.0.0.0        240.0.0.0   Auf Verbindung         127.0.0.1    306
        224.0.0.0        240.0.0.0   Auf Verbindung         10.0.2.15    266
        224.0.0.0        240.0.0.0   Auf Verbindung    141.20.212.118    276
  255.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
  255.255.255.255  255.255.255.255   Auf Verbindung         10.0.2.15    266
  255.255.255.255  255.255.255.255   Auf Verbindung    141.20.212.118    276
===========================================================================

After about 3 minutes connection goes down due to inactivity timeout and routes get deleted. OpenVPN GUI doesn't notice this.

I will append the openvpn.log.

With NDIS5 (I003 Installer) everything works as expected.

Any ideas how to hunt this down are appreciated!
I'm willing to invest some time, but I don't know where to go from here.

[egroeper]

openvpn.log for not working tunnel with NDIS6 driver

[egroeper]

The problem still exists with 2.3.5.

[Samuli Seppänen]

Does the problem exist with latest openvpn installer (2.3.5-I602)? There are tap-windows6 fixes in it.

[egroeper]

Seems like the latest 2.3.5-I602 fixes the issue. Really nice!
Thanks alot (especially to the developer, TDivine?)!
When came this out? I didn't read about it on the developer list.

btw: I tested this with my VMs: Win7 64 Bit and Win8 64 Bit.

Edit: Win8.1 64 Bit (VirtualBox VM, too) works fine.