Harford's bold move was vindicated when the big Dane slotted home the equaliser 17 minutes from time, to leave the Tractor Boys still searching for their first away win of the season.
That Jim Magilton's visitors didn't leave with more was largely down to the manager's decision to start with a 4-5-1 formation that left lone frontman Alan Lee isolated for long stretches.
The visitors' attacking options were further reduced when an injury forced the withdrawal of Tommy Miller on the half hour.
With defence a priority for Ipswich and Rangers likewise struggling to create openings, the opening period was a humdrum affair.
But Ipswich emerged after the interval with a renewed sense of purpose, and duly broke the deadlock within seven minutes when Legwinski sent a spectacular, dipping strike past Rangers goalkeeper Lee Camp from 25 yards.
Cue the arrival of Nygaard, who calmly slotted the ball past Neil Alexander in the 73rd minute to set up a grandstand finale that saw both sides spurn chances.
Jason De Vos, the Ipswich captain, and substitute Danny Hayes both went close for the visitors, but Rangers held out to condemn Ipswich to another disappointing road trip.