@LRV2021 A couple of questions:

How strong is your Wifi signal specifically at each of the switch install locations? You can get some idea by using your phone as close to the switch as possible and checking the signal strength - of course it will have to be your 2.4G network? 

Is your Wifi Network congested? Do you live in Urban area where you can 'see' a lot of your neighbours wifi networks? If so, you might try using a different channel for your own 2.4G Network to gain more band separation. (you would change the channel in your router setup)

Do you use the same SSID/PW for both 2.4G and 5G? If your router has the capability, separate them with different ID's & obviously connect your devices to your 2.4. 

One other good practice for you Smart Devices is to 'reserve' the IP's for each device so that your DHCP server always assigns the same local IP matched to the Device's MAC address. I actually use a specific SSID and P/W just for my Smart Devices and another for my other general WifI (like phones etc) By dedicating an SSID to one group of devices, you can set different channels for each, which will further help with separation. 

Your best foot forward is to delete all the devices and rediscover them, checking the tips listed above as you go. 

Good Luck!