Docking ports are ludicrously dense

Career/steam latest as of 3/9/23
I'm trying to build a space station, and one of the parts I needed was a docking hub. Despite its small size, I found that not even my strongest rocket can get it into orbit. I looked into it more and it was due to the docking ports having insane density. Rough estimation tells me that the 100% size docking port has an approximate mass of 6000kg/m^3 which is almost 3 times higher than the 2012kg/m^3 mass of batteries. I built a mockup (pictured) of the 400% size docking port and found that even if my mockup was solid batteries rather than hollow like a docking port would be, my mockup only weighs 7.05 tons to the docking port's 32.