Access point temporarily full on 2.4ghz. Is there a limit of connected devices?

I have multiple items on my network: thermostats, cameras, lights, etc. all use 2.4GHz connection switching to 5GHz isn't an option. Is there a limit to the number of devices I can have on my network? They don't access the internet consistently but do need connect from time to time which doesn't allow anyone else to use the connection they keep getting the access point temporarily full error message....full of what????