ipad wifi help

I’m hoping someone on here knows more than me about the ipad and wifi (that won’t take much!!).  I’ve had my brothers old ipad for a couple of months now and it has connected to our home wifi just fine until this week.  Suddenly it kept dropping the wifi and now it won’t even find our network while I am sitting right next to the router.  The internet and router are working ’cause our computer is wireless also and working fine.  Last night I tried renewing the lease, forgetting the network and adding it back, resetting the network settings and then adding it back, turning the ipad off and then on, turning the wifi off and then on,  I just changed the standard channel for the router from auto to 6 (found something online about that) and it still isn’t even recognizing that our network exists.  How do I get wifi back on the ipad??  Thanks for any tips or help.