My Droid Razr HD, v 4.4.2, recently has trouble connection with WiFi.  It may connect for a few minutes, or it may say the signal is not strong enough, even though the phone is inches from the router.  Other devices have no trouble.  The same thing happens when I try to connect with other wifi that used to work:  family, stores, resturaunts.  All indications point to my phone as the one with the problem.  What can I do to fix it?