I have a problem of dismounting brittle SATA ports, maybe I just need more preheating but they are sitting really tight in the board.

SATA ports are often rated for only tens to hundreds of cycles, so they're often made out of fallapartium.

If you're replacing one, it's easiest to cut all of the plastic off first, then desolder the contacts one at a time. Sometimes you can even pull the plastic off, without damaging it. It's usually necessary to preheat the board.