I keep getting a Curl error 28 when attempting to register a Connect mobile. I have tried from both Android and IOS device. I have tried using static IP as well as the FQDN. Always the same error. I have also confirmed that ports 3500/3501 are open on the firewall.
After further investigation if I disable the Geo Firewall I am able to provision the Connect app.
Confirmed it is the Geo Firewall. I only open US and Canada. When enabled unable to provision or connect, when disabled everything works,
I was trying to solve this problem, found your post, and it was indeed caused by the Geo Firewall. I am surprised there were no updates to this, as this still appears to be an issue one year on.
It looks like you can provision the VitalPBX Connect app if the Geo Firewall is disabled. It looks like you can re-enable it afterwards and the mobile client will continue to work.