The only problem is that the "StartCom Class 1 Primary Intermediate Server CA" isn't installed on the server. You always need to make sure to install all required intermediate certificates, so Firefox can build a certificate chain that ends with a built-in root certificate. *http://www.networking4all.com/en/support/tools/site+check/report/?fqdn=dc.bdev.eu&protocol=https ----- Note that Firefox stores intermediate certificates automatically, so if you have visited a web server before that has send an intermediate certificate, as might have happened in many cases, then you won't get an untrusted connection error.