wkhtmltopdf host not found error

My project is running on a virtual server. When I’m using wkhtmltopdf like this

./wkhtmltopdf-amd64 --page-size Letter --orientation Portrait --username wkhtmltopdf --password wkhtmltopdf321 --header-right “[page]” https://www.mydomain.com/project/_lib/tmp/sc_test.html /var/www/vhosts/mydomain.com/httpdocs/project/_lib/tmp/sc_test.pdf

I get the error “Host not found” and no pdf is generated (the html file is generated). If I replace my domainname with my static IP address it works.

Does anybody know what I have to configure on my linux server that the domainname can be resolved by wkhtmltopdf?

Solved - it was a DNS configuration problem.