My password was ending in an asterisk I was getting this AuthenticationError exception when calling update:
Failed to authenticate <DeviceType.Plug at 192.168.86.45 - None (KP125M) - update() needed>: Server response doesn't match our challenge on ip 192.168.86.45
I did nothing but change my password to only letters and numbers and my code worked.

I'm using the API, currently on branch for #1266