Update to iOS 26.5 prevents 2.4 ghz devices from connecting to wifi

Are you using AirPort Utility? If your Wi-Fi network uses a single (combined) SSID for both the 2.4 GHz and 5 GHz bands, your iPhone automatically chooses which band and channel to connect to based on factors such as signal strength, interference, distance from the router, and network conditions. You can determine the exact channel being used by checking your router’s administration interface or by enabling Wi-Fi Scanner in AirPort Utility and scanning nearby networks.

On iPhone, Apple does not provide a built-in way to view the currently connected Wi-Fi channel, channel width, or radio band (2.4 GHz, 5 GHz, or 6 GHz) in Settings. As a result, without AirPort Utility or access to the router’s management interface, it is generally not possible to definitively identify the specific channel your iPhone is connected to. At best, you can make an educated guess based on network behavior, but the actual channel information is not exposed by iOS.

I would recommend split Wi‑Fi bands manually

• Log into your router settings.
• Create separate SSIDs for 2.4 GHz and 5 GHz.
• Connect your iPhone/iPad to the 2.4 GHz SSID when adding smart devices.
• Revert to combined SSID afterward if desired.

Having 22 devices connected to a 2.4Ghz Wifi connection is going to be a problem. That frequency does not have enough channels to assign to devices without overlap between channels causing devices to drop out or not being able to connect at all. To compound problems with the 2.4Ghz band, it is highly susceptible to noise interference from devices that are not even connected to the network.

Splitting the bands is not a bad idea and regularly performed when dealing with older devices that have not been updated to support 5Ghz. For example, I have an old printer that connects to my network named "Home" and devices that are capable of 5Ghz connect to "Home5". Printing/Scanning continue to work just fine using AirPrint even though technically they are connected to different networks, although the same router is being used. Another example is my Ring doorbell camera that must connect to a 2.4Ghz network. I can still set it up with my iPhone connected using 5Ghz just fine.

Me too, in similar case. After my iPhone 13 Pro updated to iOs 26.5 I can’t connect to with my Apple Carplay (AION V) anymore. I did everything, restart, forget knowing network, clearing cache, factory reset for my car, but still the same. But my wife’s iPhone 13 Pro Max isn’t iOS 26.5 still connected just fine. Hope they’ll fixing this problem soon.

Helpingotherwise wrote:

After updating iPhone 16 and iPad to iOS 26.5, our smart devices could not connect to 2.4 ghz wifi.

Not every issue an individual encounters on their device can be attributed to an iOS update. If the update itself were the root cause, then every device running that same version of iOS would exhibit the identical problem. In such a scenario, the forums would be flooded with countless posts reporting the same malfunction, creating an unmistakable wave of complaints that no one could possibly overlook. The absence of such widespread reports strongly indicates that the issue is not systemic, but rather specific to the device in question.