FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Article Id 230121
Description This article describes that FortiGate can only allow a maximum of 32 secondary IP addresses per interface.
Scope FortiGate.

Sometimes, FortiGate needs to apply multiple secondary IP addresses, especially in the cloud environment.


A maximum of 32 secondary IP addresses can be created for each interface.


The message 'Command fail. Return code -4 (reached the maximum number of entries)' will appear if more than 32 are added.


Enable port forwarding if there are more than 32 internal IP addresses to map.



The maximum number of secondary IPs on each interface has been extended to 256 on FOS v7.2.4 and later versions.


Refer to the following page for more details:

Maximum Values Table