My iphone 6 will not connect to my wifi

My iphone 6 will not connect to my wifi, (iphone 5 and 4 both have no problem with it). When I tried to put it my mac address into the router, it has told me that the mac address is invalid (starts with C0:CE:)

Also, the apps seem to not wanting to connect even though I have LTE.

I have tried resetting the password, the router and the phone, as well as trying bunch of things online. Any help would be greatly appreciated