Not LLM referenced/built in any way but yea I did get a bit into personal tangents.
I wasn't trying to say that 5GHz signals interfere with 2.4 signals, but multiband equipment does sometimes suffer from full customization of 2.4 due to 5's settings. Sometimes you can work around that by disabling all but the 2.4 radio to be allowed to adjust other settings successfully. Consumer gear often removes a lot of options from the user but at least testing 2.4 only may show if you get other options or if some are altered without any UI indicating their state.
Similarly if you have a WiFi setting that is detrimental to most other devices on the band, you normally need another radio (access point or whatever). I normally degrade 2.4 as much as needed to have any devices I care about able to use it and ignore it for anything that needs performance as I'm always surrounded with neighbors who do other fun things like channels other than 1,6,11.
IoT should be isolated but for reasons of those devices often run outdated and insecure code which sometimes is so bad the only correct solution is to make sure it is kept off of the internet. "SSID isolation" could help organize that but is definitely not proper isolation in itself as you can have multiple SSIDs be one network. The real isolation starts coming from other technologies like firewall and vlan which normally can be configured to work without a focus of what SSID it connected to.
In the case of initial "I can't get it to work" troubleshooting, things that are designed to break network connection may need to be analyzed, reconfigured, or turned off for troubleshooting.