The Shots twice came from behind at the EBB Stadium to draw 2-2 with the U's - watch match highlights here.
England C's Louis John headed Sutton in front after just five minutes before Bernard Mensah equalised with a clever finish.
Veteran Craig Dundas restored the visitors' lead but Rendell levelled from the penalty spot ahead of half-time.
"We're very, very disappointed with the way we went about the whole game really," said Rendell. "It was definitely a point gained rather than two points dropped. If you're honest they deserved all three because they were on the front foot throughout the game I felt.
"We had spells but it wasn't good enough and luckily we've come out of it with a point.
"We always want three points at home, no matter who it is, that's not being disrespectful. We've got the quality to do it and we've shown that many times but it was one of those nights where we didn't go about our business in the right way.
"We let the gaffer and Rowey (James Rowe, assistant) down a little bit because we didn't do the things we were asked to do and that resulted in us not winning the game."
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