Louis Dodds and Jennison Myrie-Williams gave the hosts a healthy lead inside 20 minutes and, although the appeared to take their foot off the gas thereafter, Tom Pope made sure of the points 15 minutes from time.
The closest the Londoners came to worrying Chris Neal in the Vale goal was when Jon Nurse's deflected effort left the side-netting rippling before the interval.
"It was a tough game for us as Port Vale are a strong side," said Robson. "Physically they were a bit too strong for us. I am disappointed we conceded three and losing two early goals was a big blow.
"I wasn't sure about the penalty, but I can't complain with the results. We took some positives out of our Capital One Cup defeat at Birmingham last Tuesday but we didn't pass the ball anywhere as well.
"It's not been a fantastic time over the last couple of years for Barnet so if we can climb the league a wee bit and not be sweating at the back end of the season that would be all right. If we want to do better we've got to be better on the ball. We never had that cutting edge and never really created chances."
