kazpernzl
Hi
I manage two OpenVPN Server running Windows 2008 R2 Standard one on bare metal the other Virtualised with VMWare. Anyway we recently upgraded our VPN Software on both boxes to Open VPN Build OpenVPN 2.3.6 Both Server run OpenVPN in UDP Mode with TLS
After completing the installation we began to experience TLS sync issues and other connection issues. Where clients would connect for 10 minutes then drop for 2 minutes then reconnect again for 10 minutes. After turning off firewalls, anti-virus etc changing the mtu down to 1492 I could not solve the problem.
As a workaround on one VPN Server we used TCP which gave us a reliable connection but at a slower speed.
On troubleshooting the issue we discovered that this problem only occured due to the Windows TAP driver being upgraded to Version 9.0.0.21 installed as part of the Open VPN package. When we downgraded the TAP drivers to version 9.0.0.9 the problem went away and now we get no drop outs and are now using UDP again on both servers.
It appears that a bug exists in the Windows TAP driver version 9.0.0.21 and downgrading to version 9.0.0.9 fixes the problem.
After doing this we no longer experience any client dropouts. And clients stay connected permanently.
Thought I would share my experience, perhaps it may help someone else out there who has run into this problem.
