Within the new version of iOS and Android a new feature has been added when joining Wi-Fi's without a Password the device will automatically randomize the MAC address of the device, this is to stop listeners to build a profile of the device and thus increase user Privacy.
In some cases this will cause a device to not connect to Wi-Fi MAC or Device, in this guide we will go through how to disable Random MAC address feature.
iOS
Note that this is only enabled by default in iOS 14, iPadOS 14, and watchOS 7.
Turn private address off or on for a network
In some cases, a network might not allow devices with a private address to join, or the device can join, but the network won't allow any further access. In such cases, you can choose to turn off the Private Address setting for that particular network.
To stop or resume using a private address with a specific Wi-Fi network:
iPhone, iPad, or iPod touch
Open the Settings app, then tap Wi-Fi.
Tap the information button next to a network.
Tap to turn Private Address on or off. If your device joined the network without using a private address, a privacy warning explains why.
Android
To disable the Randomized MAC address option in Android
The randomized MAC address option is configured for each wireless connection, so there is no way to configure this just on your device. Once you connect to a wireless network, here's how to make sure the device is using a random MAC address (instead of the device MAC address).
Open the Settings app.
To disable the Randomized MAC address option in Android
Tap Network & Internet
Tap Wi-Fi.
Tap the gear icon associated with the wireless connection to be configured.
Tap Advanced.
Tap Privacy.
Tap Use Device MAC
Once this has been done within the device, you can register the MAC address of your device within Connect as per this guide.