Satellite unit on wired backhaul directly into main deco. Other satellite unit on Wifi backhaul. System is in AP mode (router functions are disabled)

System is great with 5Ghz WiFi but terrible with 2.4Ghz WiFi.  My IPhone 16 has terrible latency (90ms+) and slow speeds (sometimes slower than 1Mbps) when connecting to 2.4GHz guest WiFi or 2.4GHz IOT Wifi even when sitting less than 3 feet from the main Deco XE75 base unit.  No latency or speed problems when I connect to 5Ghz Wifi (or if I activate 5Ghz on either guest or IOT WiFi).

Various IOT devices are frequently showing as not connected - they connect and disconnect - and have poor performance on 2.4Ghz WiFI (the only option).  Some of these devices connect to the base unit and some to satellite units but it doesn't seem to make a difference to connection problems.  I have tried setting devices to connect to a specific Deco unit and I have turned off mesh technology for these devices. I have also confirmed that the system is using the latest firmware.  Regardless, given my iPhone barely works on 2.4GHz sitting 3 feet from the base it is not surprising that IOT devices are having issues when sitting much farther away from satellite units.

I have spent hours on this and my only conclusion is that Deco included the 2.4Ghz WiFi as an afterthought and didn't think it was important and so it uses a substandard radio for that band.

Since the primary purpose of this system is to allow connection of various IOT devices (temperature and water sensors, sump pump alarms, keypad doorlocks, etc.), I'm at a loss other than dumping the Deco system and going to something else ... Perhaps Ubiquiti as I believe it provides much greater control and control over individual nodes (setting channel frequencies, bandwidth, etc.) albeit in something that is much less user friendly.  Any other suggestions for a mesh system that would be similar to Deco but with properly functionion 2.4Ghz WiFi ?