Use a PKI on the TP600 as a web browser

Hey community,
I’d like to use a TP600 as a web panel, in order to display a custom web page, running on a web server on a private network. A PKI is deployed, and I’d like to allow the web page, and thus install the CA certificate on the web server.
There is a way to globally disable the certificate validation in the WBM (browser security = low), but I’d like to be more specific.

I’ve tried to add the CA certificate in the /etc/ssl/certs/ca-certificates.crt file without success.
I’ve tried to play with /etc/config-tools/config_browsersecurity but not successful either.
I still get a warning saying that the certificate could not be trusted.

If you have any idea how to do that… Thanks