Hi Silvan,
Yes, you can use IPv6 in the “Remote host/IP address” section.
Select UDP protocol on both ends. Access the CLI and check the configuration with:
cat /etc/config/openvpn
Look for: option proto 'udp6'
In case setting appears as option proto ‘udp’, open the file and edit it.
Note: To open a file with vi for editing. Press ‘i’, to enter INSERT mode, and start editing file. Press Esc to exit INSERT mode. Press ‘:x’ and 'Enter'. Changes will be saved.
Verify this on both ends, udp6 must be configured on client and server.
Kind Regards
Anthony U.