Hi @Anonymous User
I don't own a nowtv smart stick so i can not comment if during a power failure it would lose the router wifi password (i doubt it though, where the stick usually losses it power if you connect it to the television usb port every time you switch the TV into standby).
My guess it's a loss of wifi signal which is the cause, where you mentioned in your post that the wifi reception is weak or even the possibility of a faulty stick.
Maybe look at sending the nowtv stick back for a refund and look at a nowtv box over Ethernet instead or gamble on another replacement stick ?
