Cant activate 3cx licenses after upgrade to v18

[JettHelios]

Just upgraded an instance to v18, and it cannot activate the license. It says "
Unable to reach 3CX License Activation Server. Confirm that your Primary DNS Server is able to resolve activation.3cx.com" however i am able to resolve that address fine from the server. Is there an issue with the activation server at the moment?

 

[Alphabetic]

What is your DNS server?

 

[ChrisC_3CX]

Is there an issue with the activation server at the moment?

We are not facing any issues as we speak.

You might want to check your firewall configuration and make sure that there are no outbound restrictions to activation.3cx.com TCP port 443. Also check for any security services that might be running on the firewall such as packet filtering, DPI, any geolocation restrictions, etc.