If the installer still fails, residual registry entries might be blocking the creation of the virtual adapter interface.
If you use multiple VPN tools, their virtual adapters can lock resources, preventing Kerio from installing its own. Press Windows Key + X and select . Expand the Network adapters section. error 28201 kerio vpn client
VPN Client error 28201 (Often accompanied by "Connection failed" or "Unable to establish VPN tunnel") If the installer still fails, residual registry entries
Strict security software can interpret the creation of a new virtual network interface as a "bridge attack" or unauthorized change. Temporarily disable If the installer still fails