Goals from Immanuelson Duku, Oliver Lynch and Beck-Ray Enoru condemned Travis Binnion's side on another evening with plenty to be learned.
Gabriele Biancheri went closest for our young Reds in the first 45 minutes, with Malachi Sharpe also testing Lambs keeper Daniel Rachel in the second period.
The game was just four minutes old before the hosts took the lead, with Kwaku Donkor's cross headed home by Duku as the National League side dominated the early sparring.
United began to control play but just as a head of steam was being built up, the Lambs had a second, with Lynch striking after 15 minutes.