I'm changing the MAC address on my Android device; however, once I change it I get disconnected from the WiFi network that I'm connected to and then I'm unable to reconnect to the WiFi. I realized that I can connect to unsecure WiFi but not secure. I know the MAC address is changing properly because I did packet capturing with WireShark and the spoofed MAC shows as the MAC address of the packets.
Make sure MAC filtering is disabled on your router or your spoofed address is allowed to connect to the network and try again.
Perhaps the router is smarter than you thought or the Mac address isn't spoofed properly....you need to format your Android phone to be able to reconnect to other WiFi