Microsoft Dynamics CRM Online users may not be able to access their Microsoft Dynamics CRM Online environment or CRM outages may occur
If certain IP address ranges or individual IP addresses are blocked in the environment, users may not be able to reach the IP addresses used by Microsoft Dynamics CRM Online.
Ensure that all of the following IP address ranges are available and not blocked by firewalls, antivirus, or other network appliances. It is important that the entire ranges are available and not only individual IP addresses. The IP address of your CRM Online organization is subject to change without notice to another IP address within the provided ranges. As a result, if the entire range is not available, it may result in loss of connectivity to your Dynamics CRM Online organization. These ranges are solely owned and operated by Microsoft Dynamics CRM and these listed are only for hosted Dynamics CRM servers. If you are using CRM Online with Office 365, additional IP ranges will be required. See more information section for details.