Before FortiOS version 7.6.1, IPSec dialup VPN by default has Auto mode enabled where if UDP connection is blocked then the client connection will fallback to TCP using port 4500. Some environments may have TCP port 4500 blocked locally or by their ISP, therefore the default IPSec TCP IKE port is now changed to 443.

Previous CLI Behavior

config system settings
    set ike-tcp-port 4500
end

New CLI Behavior

config system settings
    set ike-tcp-port 443
end

This change applies to new FortiGate configurations only. Upon upgrade, the old ike-tcp-port value will be retained.

For information about possible conflict with GUI access on port 443, please see GUI access conflict with IPSec TCP tunnel on the same interface.