i-pad drops internet

With the prior generation wireless adapters (pre 802.11ax) it might have something to do with the way the gateway handles band steering which is one of the features of 802.11ax which is a bit different in operation than 802.11ac. I cannot say for sure as I am not a wireless expert. I have some knowledge of wireless but not enough to pull that apart. Anyway if the router added is not 802.11ax but an 802.11ac router then that might explain why the various Apple devices are happy with that as they probably are not 802.11ax possibly. I do not know when Apple started actually pushing the 802.11ax adapters out in the various product lines. I am just going to guess that the problem has more to do with the gateway firmware rather than the adapters in the Apple devices as the newer protocol tech should still allow backward compatibility. The Nokia I have does not give me grief about my older devices. Ok sure printers that only like 2.4 GHz yes indeed but most clients even older ones do work. 

Maybe it is the authentication type on the three radios are not equivalent? Check that the 2.4 GHz, the 5Ghz low band and 5Ghz high band radios have WPA/WPA2/WPA3. If the client's connection changes frequency and the authentication type it was needing is not there on the other radio it might cause the failure. It is one thing that can be checked just to know and be sure.