Hello,
Just to confirm, is the INKBIRD logo on your IBS-M1 blue or gray? Did you clear the sub-device by long pressing the RESET button on the side of the gateway?
Please understand that if you long press the WIFI button in the middle of the IBS-M1, it will reset the WIFI connection.
If there is an offline IBS-M1 in the INKBIRD app, please delete it and add it again. Does it work?
Please make sure the router is set up correctly, please refer to: