My ChemDraw activation fails with a general communication error

On activation you may need to allow communication to the activation server through your
firewall or proxy server.

If activation fails, please work with your IT organization to allow communication with the
following URL:

https://revvitysignals.compliance.flexnetoperations.com/deviceservices

If you require to whitelist IP addresses instead of a URL, please use the information below.  Because the server is now on AWS, the IP address can change and there is not a unique IP address to whitelist:

IPv4: 185.146.155.0/24
IPv6: 2620:122:f003::/48   

The port used is Port # 443.