My guess is OP had a spare AE laying around so he’s using it as a defacto network switch to add ports to the end of the cable that runs back to his router. Connecting it directly to the network caused him issues because he didn’t disable its DHCP server, and the fix was to put it in client bridged mode (which disables its DHCP server function).
A single box that does modem/router/wifi is a simple solution, and cheap, and convenient, and usually works OK. However if you want to ramp up your network performance then you should consider using a dedicated cable modem, connected to which is a dedicated router, connected to which is a dedicated network backbone switch, connected to which is an access point, the wired network clients, and any other network switches acting as remote hubs in those places where a single cable needs to connect multiple devices.
There are different flavours of network switch: managed, unmanaged, AV priority, pre-configured VLAN, all with or without POE. An unmanaged AV priority switch is a good choice because you don’t need IT knowledge to configure it. You just connect those devices which need the higher priority to the appropriate priority port on the switch. So, latency sensitive devices such as VOIP or those streaming audio/video get the high priority ports, the control system or access point might get medium priority ports, and printers and computers etc get the low priority ports.
In this instance I suspect the OP just needs to replace the AE with an unmanaged 5 or 8 port network switch, for which there are many choices for $100 or less.