First of all, Webinoly does not even have a firewall. So, I don't know why you can not connect through an specific port.
If you are using our "reverse proxy" site configuration, you should check if you have something blocking these ports, like an external firewall that is included almost with all cloud providers.
If you are trying to connect your app/agent through a "normal" site, these sites are configured to only listen port 80 and 443, in this case you have to use your own custom nginx configuration.
Are you the owner of "zabbix" or why are you requesting a collaboration between these two tools?
Best regards.