I have to create a sub domain. Runs fine. But when accessing to it, I have the ugly advertissement about non ssl certificate for this subdomain. I've remade Let's encrypt certificate with * in subdomains combobox, but it doesn't work. What am I missing ?
You can't use * for LE certs in ISPConfig. Create the subdomain with the right name in ISPConfig and it gets added to the SSL cert of the site automatically.