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.

Note:

If you are using Zscaler, you will need to contact Zscaler support to whitelist the ports and URL listed above and to allow the use of QUIC protocol on these ports/URLs.  

Due to the nature of Zscaler and the QUIC protocol, the connection may still fail around 20% of the time.  If this happens, just try activating a second time.

Also Note this announcement about certificate changes by our download/activation vendor, which may be relevant:

SSL Certificate Change for Download Center – Revvity Signals