Do Some Wifi Routers Have A Security Key Even After Reset

So I decided to reset a wifi router, I have done this many times before and each time the process was quite smooth. But those routers were different models.This particular one is quite something. I reset it and when I tried to connect back to the network it asked me for a security key! I have tried everything from admin, password, 12345, the old passwords it had.. nothing seems to work.It gives a 'limited connectivity' message and the diagnosis tool asks whether the security key is correct. And it only accepts five characters (alphanumeric)So obviously I cannot try the default IP in the browser to access its settings, I can't even connect to the router.Are there known routers that ask for a security key even after resetting?