Small home network. Few ipads, 2 laptops , iphone and a galaxy. Apple tv works. Ipad always connects, no problem with iphone, one laptop works, but the ipad mini will not show wifi symbol and the galaxy does. But does not connect to network as control app fails to work and one new win7 laptop will not connect to internet, only to network. Rebooting router corrects this and it is frequent. Its a basic pos d-link router. I know, change it. But I am the type that likes to see if there is a known issue and fix before just swapping. Because you might learn something. Any ideas?

Did you Fing it and check for duplicate IP addresses?

If it is a dual band router, turn off the 5Ghz radio
I have seen some devices that are picky if two radios have same SSID.

Turn off wifi security for testing, is/was it set to WPA2/AES?

Did you try a test router just for good measure?
Replace the router, it is past it's expiration date.

iPad mini no wifi symbol?
Airplane mode off
Hard reboot device
?

Did not fing or replace, it is not dual band. It is past its use by date. I did not turn off security and security is as you mentioned. Ipad mini wifi symbol off, airplane mode odd and did a hard reboot and network reset. Rebooting router fixes issue with all three troublesome devices.