Don't overlook the basics. Ensure your remote IP address isn't being blocked:
According to the official changelog, Kerio Control VPN Client 9.4.2 focuses on:
In practice? The IPv6 support works, but only if your Kerio Control firewall is also on version 9.4.2 or higher (patch 2 is mandatory, or you’ll see dropped routes).
For version 9.4.2 to function correctly, the user’s workstation typically needs to meet the following criteria:
Yes, if:
No, if:
A known bug in Kerio Control 9.3.x causes the client to hang on IPv6 routes.
For network administrators and remote workers relying on Kerio Control for secure access, keeping the client software up to date is non-negotiable. The release of Kerio Control VPN Client 9.4.2 brings essential maintenance fixes and security refinements that ensure seamless connectivity for Windows users.
If you are currently running an older version, here is why you should consider updating to build 9.4.2. kerio control vpn client 942
Build 942 does not have a native kill switch GUI, but you can enable it via PowerShell:
# Block all non-VPN traffic if tunnel drops
New-NetFirewallRule -DisplayName "Kerio Kill Switch" -Direction Outbound -Action Block -RemoteAddress "0.0.0.0/0" -InterfaceAlias "!Kerio VPN Adapter"
Since upgrading to 9.4.2, many users are seeing:
"VPN Server not responding. TLS Handshake failed."
This is rarely a network issue. It is a certificate issue. Don't overlook the basics
Kerio Control 9.4.2 is much stricter about certificate validation than 9.3.x was. If your firewall is using a self-signed certificate with SHA-1, the client will reject it.
The Solution:
Do not use the old trick of checking "Ignore certificate errors" in the client config. That checkbox has been deprecated in 942 and does nothing for the initial handshake.