The young Reds fell behind to Jack Roles’ strike early in the second half and could not find a way back into the game with 10 men after Adam Lallana was shown a red card.
George Johnston was dismissed for a second bookable offence in the closing moments, too, on a night that Neil Critchley’s side will want to forget.
The U23s were boosted by the availability of four first-team players in Danny Ings, Lallana, Dominic Solanke and Ben Woodburn – all of whom started at the home of Stevenage FC.
Chances were created constantly in the first half and Solanke might have put the Reds ahead from either of two quick-fire openings forged by strike partner Ings on four minutes.