Jaydan Davidson hit the post for Derby early on, and his team-mate Lennon Wheeldon went one better just before the half-hour mark, when he rounded United goalkeeper Thomas Myles to give the visitors a half-time lead.
The Reds had to remain patient in attack to get back into the contest, with a triple change on the hour mark helping to change the course of the game.
Ethan Wheatley was among the trio of reinforcements, and within 10 minutes of coming on, he struck our equalising goal.