Hm, I don’t know.
Booleans can be tricky. They are very sensitive to modeling ‘mistakes’. Double check the ‘cutters’ for double Vertices, inconsistent Normals and holes.
I actually find the fact that you had to switch the first port to Fast already a bit suspicious. Try disabling that Boolean and see what happens to the ‘second’ one.
Or disabling the other three Booleans and only look at the two ports…
If you still can’t get it to work, you can post a link to your .blend and we can have a look.
