How to use a self-signed certificate -> correct https://gitlab.com/CardBook/CardBook/-/wikis/server-configuration#--2
On https://gitlab.com/CardBook/CardBook/-/wikis/server-configuration#--2 it says:
Note: The connection via https will fail if there is only a self-signed certificate for the domain (as is the default). Therefore you will need a recognised certificate.
This is not true, I successfully use the standard self-signed certificate of my Synology DSM with CardBook. Here is how I did it:
Go to Thunderbird -> Preferences -> Advanced -> Certificates -> Manage Certificates -> Servers -> Add Exception …
Fill in the whole URL including the port number (e.g. 8443) in the Location field. Then click on “Get Certificate”.
Tick the box “Permanently store this exception“.
Finally “Confirm Security Exception”.
Now you can add the address book to CardBook.