The Zendesk proxy server has an invalid IP address 

We're using a Zendesk proxy server to make secure requests to third-party servers that have IP address protection. They always allow a list of Zendesk IP addresses to make it secure.

It worked all the time, but now it has become random - one-day Zendesk proxy server uses the Zendesk IP address, and the next day it uses the client IP address. So, we can't use our Zendesk apps because we can't allow list client IP addresses for all agents to make sure it works.