Hello RM89, 1:Many NAT will be used when you have 1 public IP and it is NATed to several LAN IPs. In this case, you have several Public IPs, I assume they are from your MX's WAN subnet itself. You will need to use 1:1 NAT.  Doc: https://documentation.meraki.com/MX/NAT_and_Port_Forwarding/Configuring_1%3A1_NAT Make sure those Public IPs are active from your ISPs end and ISP gateway receives ARP responses from those IPs. ... View more