Apple has made announcement that the will be Deprecated Kernel Extensions and System Extension Alternatives
https://developer.apple.com/support/kernel-extensions/This will / can have impact on users on MAC using Tunnelblick to connect to SME servers with the OpenVPN Bridge.
Here is the notice from Tunnelblick :
https://tunnelblick.net/cTunTapConnections.htmlIf you have a 'tap' VPN, a future version of macOS will cause your VPN to stop working. (Apple's announcement to developers is worded differently and may mean that users will be able to use some mechanism to enable 'tap' VPNs to continue to work, but that interpretation is contradicted by the warning shown above. See What Apple announced, below.) On macOS Big Sur you may be able to allow 'tap' VPNs to continue to work by disabling SIP. You may be able to convert your 'tap' VPN to a 'tun' VPN which will work. However, that requires being able to change the OpenVPN configurations on both your computer and on the VPN server, and it may not provide all of the networking facilities that you are currently using. Consult OpenVPN experts and support for help with doing this.
they go on to say the vpn's using tun interface users using Tunnelblick should still be able to connect.
If you have a 'tun' VPN, your configurations may continue to work in future version of macOS without you doing anything, or you might need to make a simple change to the OpenVPN configuration file so that the configuration will continue to work. If your OpenVPN configuration file does not contain a "dev-node" option, you do not need to do anything and the configuration will continue to work. If your OpenVPN configuration file does contain a "dev-node" option, you will need to remove that option so the configuration continues to work (see below).
From my understanding, SME servers running OpenVPN Bridge with Mac clients connecting, may well have to install the
OpenVPN Routed contrib as well, and set up the Mac users to use the OpenVPN Routed contrib.
OR, Install alternative vpn solutions ( Libreswan , SoftEther ect ).
Thoughts ...