joerack:
Question is: what if the router isn't working? Am I locked out?
I'm sure you will find clues in the data sheet of the actual lock on how your particular lock would deal with this.
There must be a failsafe solution in this case... like a loopback check on lan.
For my home: the RCB is on the outside wall. Could just trip it, power goes out, and such a lock opens. Now I wouldn't say that "lock opens when power out" isn't exactly fail safe in itself. How about a physical key as backup?