While the Deco-Mesh works well for modern devices on 5 or 6 GHz, I still (ever since) struggle with IoT-Devices on the 2.4GHz band and I know that I am not the only one. The basic problem I see ist that we set up APs to suit well WiFi 6/7 devices and will then have much more overlap on the 2.4GHz band as these waves spread farer especially the more obstacles there are. This appears to be the problem for IoT devices located precisely in such "overlap zones" with all antennas at the same channel. In addition, these devices are stationary and therefore have no chance of improvement. At best, they can hope that a door or roller shutter will close to better shield one AP. The question of power control for the antenna has already been asked and answered rather negative. However, it would really help if this could be done for the 2.4 GHz band at least. 

Alternatively, it would also help to remove the 2.4 GHz band from the mesh entirely (but still provide band steering) and then set the channels for this band individually on each Deco (or even better: the automatic search would then assign individual channels for each Deco on 2.4GHz). I think that hardly anyone today would want to use the 2.4 GHz band for mobile devices and would rather prefer to set up an additional AP for better throughput on 5 or 6 GHz. Stationary devices do not require mesh, band steering, or roaming and  they often outnumber the mobile devices by far.