Sorry, that part of the setup I'm not doing the same. I had to go
back and reread your original post. Mine is down to 4" by the time it
hits the power tool.

Actually, you have already answered my question. You are transitioning
from 6" hose to 4" connection right before you reach the machine. OK.

BTW: If you know of a decent 4" quick disconnet, let me know. The
one on my planer stinks.

Likewise.

I saw in a dust collection book that the author uses a metal connector
for quick connection which doesn't look like the plastic/rubber one
that is widely available. I think I will go looking for it.

Jay Chan