Block an unrecognised MAC address from wifi that the router filter can't block

Sobreacain

Reputable
Mar 22, 2014
1
0
4,510
I have an address that doesn't match any devices in my house showing up on my wifi network. Changed admin pass for router and changed wifi password to 63 character pseudo random key as soon as I noticed it. But although the devices I haven't updated with the new password yet no longer show up on the network this one does!

Tried blocking by MAC address on the router but it's still there. Even though when I tested blocking my own devices the same way it worked fine and kicked them off.

Any ideas?