Option activate OTAU

You mean in the old web app ? I can’t see it on Phoscon …
If I m right it enable automatic OTA but only for router (the procedure is heavy for sensor, can be bad for battery).
You just need to put your firmwares file in the OTAU folder

ZigBee firmware is identified by the Manufacturer Code, Image Code and Version. On startup, the STD OTAU plugin will read all *.ota, *.ota.signed, *.sbl-ota, and *.zigbee files in ~/otau, and copy them to mmmm _ iiii _ vvvvvvvv .zigbee files, matching these attributes.