I assume this is so they can pull a DB9 through it with the shroud in place.
There is no such thing as a DB9..
The correct designation for the 9 pin D-subminiature connector is DE-9. The second letter designates the connector shell size.
Using the standard #22 contacts, the sizes are DA-15, DB-25, DC-37, DD-50, and DE-9.
Other inserts are available, such as DB-13W3 (3 coax or high-voltage contacts + 13 #22 pins, used for older Sun monitors.)
source: ITT/Cannon D-subminiature connector catalogs, 1947-present. (my copy is a 1971 printing of a 1969 edition, which agrees with the current pdf version.)
Other common errors are RJ-45, which actually designates a specific connector, wired in a specific wiring pattern, for a specific telephone application having nothing in common with Ethernet. (if you use the specified connector, it not only won't fit into an Ethernet jack, but the wiring will have no wires in common with Ethernet.)
source: 47 CFR 68.502