iPad no longer sees my home router

After upgrading my Mac Mini to OS X 10.10.5, my iPad Mini, on connecting to my home Wi Fi, it no longer sees my router. Outside, the Mac Mini will still recognize and connect to free, public Wi Fi. How do I get my Mac Mini can access my home Wi Fi router again?

Could the OS X security update have done something to block access to my router and if so, how do I fix it?