The Tractor Boys had five in midfield leaving Kevin Lisbie up front on his own, but it was the Swans who went ahead after just 141 seconds.
Serran raced up the right flank leaving two defenders trailing before crossing to Scotland, who crashed the ball home from close range for his 14th goal of the season.
Swansea kept up the pressure and Ashley Williams burst through but Richard Wright was in position to gather safely.
The visitors were second best all over the field as Dyer and Mark Gower were brought into the game at every opportunity, but an attempted clearance by Williams gave Town a corner on the half hour only for Alan Quinn to blast high over the bar.
A minute later, Garcia Jordi Gomez and Scotland combined but Richard Wright stretched high to collect the loose ball.
Town replaced ineffective midfielder Jon Walters with another striker in Pablo Counago as they reverted to their normal formation for the second half.
The move seemed to spark the visitors into life and David Norris went close in the 51st minute with a shot that drifted just beyond the far post and then Tommy Miller was set up by Counago but he was also wide with a low drive.
Gower skimmed the bar after cutting inside as the Swans began to put a few passes together in response to the visitors' improved second-half display.
The increased pressure brought the Swans a second goal in the 73rd minute when Scotland twisted and turned to create space before leaving David Wright standing and smashing a shot into the corner of the net.
The Swans were now back to their best and Ipswich were forced to defend desperately as Scotland went looking for a third goal.
It came in the 86th minute when Gomez struck a 25-yard free-kick into the net leaving Richard Wright grasping in air and the Swans deservedly ran out comfortable winners.