Confirmed. Portal 2 (2nd Drill Hall) does work, but only while you're on a Knighthood Exam quest — that's authentic v83 behaviour, not a bug. The other three Drill Hall portals point at training maps that aren't imported into our world yet, so they can't be shown or used until those maps are extracted. That extraction is the real fix and is tracked.

Fixed on develop (live at next publish). All four Drill Hall doors work now. Portal 2 (2nd Hall) already worked; the 1st/3rd/4th doors pointed at training maps we had never imported, so they were hidden/dead. I extracted those maps (the 1st Hall variants, the 3rd Hall's boss 'Snipe of Competence', and the 4th Hall's 'Advanced Pianus'), registered the two bosses, and wired the doors. Since these are useful to everyone, they are now OPEN TO ALL CLASSES (beginners included), not just Cygnus Knights. Each is a solo instance (one player at a time, as in v83). Re-test all four portals after next publish.

Live in the latest publish — marking this Fixed. Thanks for the report!