Ipad Air 2 see WI-Fi but will not connect. Will connect via Personal Hotspot

Hi Team , I have my very first iPad. It's an Air 2. I can connect my iPhone, 3 x Latops and Media Player to home Wi-Fi. IPad sees my Wi-Fi but will not connect. My iPad will connect via my iPhone Personal Hotspot and will to my work Guest account. I am running a Motorola SBG900 cable modem. It is old but all my other devices have no problem connecting. I have reset, rebooted, restarted everything from at least a dozen suggestions. I would buy a new modem but am fearful that it would be $2000 and still not work. Any input appreciated. Tag ..you're it... M