A connector, shaped like DB-25 (male, PCB-mounted), except it has only 9 pins: 5 normal ones in the regular two-row pattern you'd expect, and 4 much larger coaxial ones - 1 on the left and 3 on the right.
https://media.mstdn.io/mstdn-media/media_attachments/files/115/638/468/484/829/682/original/6de79659295d2bfc.jpg