Paul beat the Portland cover defence to cross in the corner.
But that try was a fleeting moment of Otangarei offence in the first half as Portland picked up a penalty shot at goal before scoring again out wide.
Portland fullback Stilie Antonio produced another strong performance at the back and was rewarded with a try off an incisive burst, stretching his side's lead to 18-4.
Centre Jordan Katene hit back shortly before the break for Otangarei however, a try on the siren from halfback Wayne Iripa restored the 14-point deficit at 22-8.
Otangarei returned a different outfit in the second half, replacing indecisiveness with precision on the attacking end as they charged back into contention.
After an extended and well-defended raid on Portland's line, the weight of pressure eventually reaped rewards as second-rower Petero Blake crashed over the line.
Portland began to tire midway through the second half as Otangarei found their outside backs on a more consistent basis as they proved threatening with every touch.
Centre Dominic Ormsby dominated proceedings in the last half hour on the left edge, scoring two tries in less than five minutes - one a simple break, the other a quick tap that caught the defence napping.
Tries were coming on the opposite edge as well with Blake grabbing a second to extend their lead to 28-22.
Ormsby capped off a sublime second half effort by completing a hat-trick after again catching the defence off their feet.
A final try on the right edge to Shane Herbert ended the encounter as Otangarei's 28 point burst enough to topple Portland.
Meanwhile, Moerewa Tigers continued their strong start to their RLN Premiership defence by beating Hora Hora Broncos 46-16.
Moerewa dominated the match-up as they added a third win from as many contests to start the 2018 season.
Hora Hora were far from embarrassed however as they provided a staunch effort on both sides of the ball.
The final match of the third round was a one-sided affair as Takahiwai Warriors made light work of Northern Wairoa Bulls.
Takahiwai ran out with the 60-18 win away from home.