Very nice, thanks IzNoGoD, config works great.
The missing command to generate dhparam.pem: openssl dhparam -out dhparam.pem 4096
There is an option in vBulletin to "force" a URL, which could be https:// then, but http:// wouldn't work then anymore, but rewrite all URL's directly to https:// then. I kinda wanna keep both, http:// and https://, I hope they gonna deliver a real answer in the vBulletin forum. ATM just crap like "activate that option muh". Maybe only allow https:// after all? Dunno if that could cause problems for some people.