Downlink problem

when I sent by the TTN console any downlink msg to a device with a fixed SF12, this didn’t cause any change in the “Frames down” counter that always remains zero.
Of course the node didn’t execute any of these command.
I’ve also deselected the “Frame counter Checks” in the setting of this device, but with any result.
I’ve also reset the frame counter that will become zero for a while, but when an uplink arrive it assume the old counter value plus one (i.e. 16756).

gateway, node, ecc? Remember that the downlink will be sent only after receiving an uplink.

Thanks for the suggestion, but unfortunately this node send an uplink every 15 minute and that’s the reason I’d like to send a downlink for change the uplink interval.

still missing info to help.

The node is an Elsys ELT-2-HP like another one that works fine, the gw is a Lorank8.
The Frame down counter is incremented anyway when the TTN backend send a msg to the gw or only if there is a feedback from it ?