WaiBop opened the scoring in the 37th minute after a good passage of play where the visitors held the ball well in midfield.
Jackie Pretswell then put a well-weighted ball behind the Northern defence for her team's prolific goal scorer Helen Collins to use her pace to beat the defence and open their account with a quality finish.
Collins, a former age group international, netted 43 times over the winter season and shows no signs of letting up at ASB Women's League level.
However, the lead lasted a matter of minutes as Northern's Laura Mathis bundled the ball home after earlier hitting the woodwork to have the teams level at halftime.
Smith said his players were comfortable at the break and quietly confident of getting something from the match.
But in the second spell, Northern's experience titled the balance in the hosts' favour and goals in the 63rd minute to Tessa Berger and 79th minute to Tayla O'Brien left WaiBOP chasing the game.
Both of Northern's second half goals resulted from set piece plays, with Berger's header coming from an Estelle Harrison corner, while Tayla O'Brien sealed the points in emphatic style, unleashing a top far corner special from the edge of the area after WaiBOP had failed to deal with an earlier corner.
Smith was confident the defensive errors could be addressed on the training pitch.
"It's a good learning curve for our girls as Northern's goals came from periods in the match where we momentarily switched off. However, we've identified this and it can be addressed; when you're up against quality opposition you just can't do that."
Smith said he was happy with how the WaiBOP team were comfortable in possession as this is a focus at training.