Chances are you may come across an issue with your Ubiquiti UniFi configuration. If you’re making changes to your network/UniFi controller, then you may come across an error saying that UniFi adoption failed. This is mostly due to changes made(e.g. changing IP subnet) which prevents your UniFi device(s) from phoning home to the controller.
In order to resolve this particular issue, you will need to reset your UniFi device first. The reset button is usually located right next to the ethernet port of your UniFi hardware, and requires a needle-sized tool to press and hold until it lights up again. This will factory reset the device so that it can be re-provisioned.
Once done, open up your UniFi controller and head over to “Devices”. You should see your UniFi device listed with the “adoption failed” error displayed. Click on it to open the properties window.
You will now see a + sign to the very right. Click on it to bring up the adoption section. Make sure the Inform host address is your controller’s IP address. If the Port is blank, go ahead and type in 22 for the port. In most cases, the default user and password for UniFi devices are either ubnt/ubnt or root/ubnt. In my case root for the user and ubnt as the password worked.
Once you’re done, go ahead and click to adopt. Your UniFi device will utilize SSH in order to download configuration information from your controller such as your SSID(s) and security configuration.
Your device should now be working. If not, head over to your controller’s Settings->Controller.
Make sure your Controller Hostname/IP is set to the IP address of your UniFi controller. Click the box next to Override inform host with controller hostname/IP to check/enable it. After, click Apply Changes. Go ahead and adopt it once more.
Note: If your UniFi Controller is running remotely on the internet, you will need to allow TCP port 8080 and UDP port 3478 on your server/network firewall for adoption to work properly.
You can also adopt your UniFi device through SSH. Look here for more information.