Simple Solution (TesiraFORTÉ X) does not fall back to Link Local

If you're FORTÉ X does not fall back to Link Local (an adress in the 169.254.x.x /16 range) when this is desired, first step is to make sure no DHCP server is able to reach the FORTÉ X.

Secondly, you need to be aware of that when switching between port modes, if DHCP addresses have been acquired by the device's interfaces previously and a new DHCP server do not present the device with new IP information, then it may take
up to 10 minutes for the device to release the old DHCP addresses and fall back to link local.

If the FORTÉ X still does not fall back to Link Local, make sure to reboot the device.