Import root certificate in Synology

I am looking for a way to import a root certificate in a synology server (the certificate comes from a ssl intercepting proxy).

I have copied the certificate to

/usr/share/ca-certificates/<somesubfolder>

And changed the permissions to 744 and owner to root:root. Then I made a symlink to the cert in

/etc/ssl/certs

This didn't change a thing, so I additionally modified the file

/etc/ca-certificates.conf

and added the line

<somesubfolder>/<certfile.crt>

Again, this didn't change the behaviour, still no connection possible to the outside world. Any ideas?