Are antinomies beyond reason?

Hello,
In one of the videos circulating on the Internet, I heard a quote that I always agreed with, until I thought about Kant's antinomies, in which the rabbi said: "There is no such thing as beyond reason, it is nonsense from people who don't know how to reason things."
So my question is, don't antinomies point to those things that we cannot in principle understand with our minds?