@Bigjimcfh 

Would you be able to give us some more information on your exact setup?  namely where the DHCP is coming from and what address your AP has at present..   You mentioned Deco, is this to link into the deco ecosystem?

  @Philbert 
Currently I have ISP Modem (1.2gbps) bridged to Deco M5s in Router mode assigning DHCP to all devices Wireless and wired.

EAP is getting assigned an IP.  On same network, I have the server running the Omada controller software. 

In Omada controller, I see EAP as having IP assigned successfully via DHCP and I can connect to EAP via web browser or controller.  Controller shows EAP as green "Connected".

As mentioned, on my clients (M1 Macbook, Dell Laptop, M1 Mac Mini, Lenovo Laptop) they all connect successfully to new EAP and transfer data as expected, and at faster rates than DecoAPs, also as anticipated.

iPhones only seem to not want to cooperate with this EAP it seems
 

  @Bigjimcfh 

It does sound like you have covered most of the angles of diagnosis there, however from experience this could be the WPA settings for your WiFi.

Are you running WPA3 SAE by any chance?   If so seen that not work with iphones before, create a test SSID and give it WPA2 AES and see how that works (if it does). 

Any perticular flavour of IOS?   eg all running 16 or a mix bag?