Remove the check from 'Disable IPv6 unless the server is accessed via IPv6'.

Select the configuration(s) you wish to modify.

Click on the large 'Configurations' button at the top of the window.

Click the Tunnelblick icon in the menu bar and then click 'VPN Details'.

If you cannot confirm that, you should not proceed and you will not be able to use Sidecar when your VPN is connected.

Verify with your VPN service provider that no information is leaked if IPv6 traffic is allowed.

This is done to prevent information leaks in common VPN setups (see A Glance through the VPN Looking Glass: IPv6 Leakage and DNS Hijacking in Commercial VPN clients).

By default, Tunnelblick disables IPv6 while a VPN is connected. Sidecar does not work if IPv6 is disabled. WON'T FIX: Sidecar does not work when a VPN is connected using Tunnelblick's default for a configuration. If your VPN requires the Tun system extension, you can вЂ“ and should вЂ“ modify your OpenVPN configuration file so the system extension will not be required. Tunnelblick will be able to load Tun and Tap system extensions for any configuration without user interaction, and that ability will persist after computer restarts, 'safe boots', and updates to Tunnelblick. Once permission to load system extensions signed by 'Jonathan Bullard' has been granted and the computer has been restarted, no further action is needed. Save the configuration file and quit Start the VPN connection by clicking on the Tunnelblick icon near the clock and selecting the Connect Zeroshell item. After the permission has been given and the computer has been restarted, you may then connect all VPN configurations normally. If the user gives such permission by clicking 'Allow', macOS must restart the computer before the permission will be honored. If a configuration requires a Tun or Tap system extension, the first time Tunnelblick asks macOS to load the appropriate system extension, macOS will tell the user that they must give permission to load system extensions signed by 'Jonathan Bullard' in System Preferences : Security & Privacy : General.

NEW macOS REQUIREMENT: Restarting the computer is required by macOS Catalina before connecting some configurations for the first time. To report an issue, please follow the instructions at Tunnelblick Issues. The following is the current status of issues that have been seen using the latest stable version of Tunnelblick on the latest version of macOS Catalina. You should allow Tunnelblick to automatically check for updates on the 'Preferences' panel of Tunnelblick's 'VPN Details' window. If you are using macOS Catalina, you should use the latest version of Tunnelblick. Important: See The Future of Tun and Tap VPNs on macOS for information about changes to future versions of macOS.

Tunnelblick ovpn mac client