FortiSwitch PoE fails to power MikroTik Cloud Switch

Hi,

we use a bunch of FortiSwitch-448E-FPOE for different puposes. Two of them are used for management access to different devices - two of them being MikroTik CRS309-1G-8S+.

The problem we face is, that those MikroTik switches can be powered by PoE but no matter what settings I apply to the FSW ports PoE-wise, the FSW won't deliver power to the MikroTik switches.
When I use a HPE 2530 switch or any PoE+ capable power injector, the MikroTik switches get powered by PoE like a charm.

Has anyone else experienced this phenomenon? I did not yet create a case with support, just asking the community first.

Thanks for you input!