Hello

So there are two solutions to connect to a wireless network when iOS devices (Apple) get the error "Unable to join Network"

The first solution is to manually add the wireless network. This is done by choosing the "other" option under wireless networks.

You input the name of the wireless network (as written) and choose "WPA2" for security from the drop-down options available when choosing the type of security the wiresless network was configured with. This may be different depending on the wireless setup. These options can be found here if you click on the drop-down box to view the options on this screen. After this is chosen you can back out from this option screen and it will take you back to where you can input the name of the network and password. You'll know that you chose the correct security option as it will not appear on this screen. 

At this point all you have to do is enter the password. 

If after performing the above steps and you still can't join the network there is another solution.

You will have to reset the iOS devices' network settings. This will delete all networks currently saved so you will have to re-enter passwords for networks you were previously at. Try finding the wireless network automatically instead of inputting the information manually. 

"From personal experience, the “unable to join network” error seems to occur when connecting to certain Wireless N routers more often than anything else, so if you have a dual band router you may just opt for the other network option and skip the troubled signal. Sometimes restarting the router can help too, but since not all users have control over that, it’s generally best to offer an iOS client specific resolution." Taken from article below:

http://osxdaily.com/2014/03/01/unable-to-join-the-network-error-ios-fix/

Hopefully this works and thank you.