Source: https://gonza.fi/en/unifi-incorrect-password-ios-iphone-ipad

The Unifi line of WiFi access points from Ubiquiti have a strong reputation for being reliable devices. However, many users are reporting “incorrect password” errors when using premium mobile devices from Apple. Fixing this issue is easy using the Unifi controller WiFi settings.

The reason for the error is WiFi management done on iOS devices. The default settings for the Unifi range are not compatible with iOS 11 and 12. The reason for the error is the “DTIM Mode” that has to do with the beacon timing setting due to power saving. The default value for the Unifi WiFi devices is 1, but it is recommended that this be set to 3 or higher by Apple.

The remedy is to done using your Unifi Controller. Open the administration interface, go to setting and select WiFi. Then select the WiFi where iOS devices are experiencing the “incorrect password” error. In this section you can apply the configuration steps with the following steps:

– Open 802.11 Rate and Beacon Controls
– Uncheck DTIM Mode checkbox for Use default values
– Set DTIM Timing to 3 for both 2G and 5G

That is it. This configuration works better with the power saving features of iPhone and iPad devices on a WiFi network powered by Ubiquiti Unifi wireless Access Points.

I am using a 1st generation Ubiquiti Cloud Key to manage the network so:

1. Settings > WiFi > WiFi Networks
2. Mouseover the network name and click on Edit on the right side
3. Go to: 802.11 RATE AND BEACON CONTROLS
4. Toggle on: Override DTIM Period
5. Set both 2G and 5G DTIM Timing to 3

Also: Go To Sleep, Go To Sleep, Go To Sleep Little iPhone https://www.sniffwifi.com/2016/05/go-to-sleep-go-to-sleep-go-to-sleep.html