سلام ،
اینجا جواب سوال‌تون هست :

کد:
http://docs.whmcs.com/ResellerClub

متن :

CURL Error: 7 - couldn't connect to host

This error message indicates that you haven't yet allowed your servers IP to access your ResellerClub account via the API. You have to do this in the Settings > API section of the LogicBoxes control panel before you can use the integration. The IP you need to authorize is typically the main shared IP of the server, usually most easily found from the IP your WHMCS license is assigned to, but if you're unsure or neither of those IPs work, then ResellerClub can assist and advise you of the IP they see your connection tests as coming from via a support ticket.