which port is kacar using to connect the host servers ?
I don’t think the port matters. If it did, it would have been mentioned in the documentation or on the developers site.
As far as I know, kACARS uses the site URL to connect. And since you have issues getting all ACARS clients (kACARS and several other reporting systems) to connect, the issue is with your site.
All the acars for phpvms 5.* use the post and get protocol with the included php bridge file