D. Drexler was a 22nd century member of United Earth Starfleet, one of the officers listed on the dedication plaque of Enterprise NX-01. Drexler was listed in the group of names of those credited for contributions to ship's spaceframe engineering. (Star Trek: Enterprise set artwork)
This character Drexler was named for production staff associate Doug Drexler. This name did not originate in the dialog or script of a canon production, but was featured on a piece of set artwork. Coincidentally, Drexler also played an unnamed Starfleet ensign of the same era, as an extra in a cameo role that might be the person referred to here. It remains to be seen whether that character might've actually had the name "D. Drexler" on his uniform nametag.