Active Protection Systems* could be blocking, filtering, dropping, or modifying network packets from a PCI Certified Scan. Such behavior could affect an ASV's ability to detect vulnerabilities.
A new subnet has been recently added for scanning services:
You can see a full list of our IP ranges that should be allowed here if you are receiving scan interference.
Please note that these IPs are specific to our scanning services.
*Active Protection Systems could include any of the following; IPS, WAF, Firewall, NGF, QoS Device, Spam Filter, etc.