You went a little over my head regarding the DNS over TLS, but the IoT network is for less secure devices. Perhaps some component you are using for this, is not capable of using higher security.
Do you have your system set up with MLO enabled? Are you using Smart Connect? You iPhone does Wi-Fi 6e, but not Wi-Fi 7. If you have MLO enabled, and the S24 Ultra does Wi-Fi 7, you may see indications like the one below. The attachment came from a Windows 11 Desktop system running the Windows Insiders version.
Do these disconnects happen when you have a strong Wi-Fi signal?
If you wanted to check your log, each radio has a specific identifier. If you take the MAC address of that radio, you may be able to follow it through your log.
I still have a small problem that needs to be addressed, and that is a non-WPA 2 device being allowed on the IoT network and then kicking my home alarm system, which is WPA2, off the IoT network. I am running the Pro version of the router.
