Well well well... Here's a clue! Found this in a zone log.
[08-23-2017 :: 19:31:53] [Quests] Tying perl output to eqemu logs
[08-23-2017 :: 19:31:53] [Quests] Creating EQEmuIO=HASH(0x558111f1f710)
[08-23-2017 :: 19:31:53] [Quests] Creating EQEmuIO=HASH(0x558111f2fd7
[08-23-2017 :: 19:31:53] [Quests] Loading perlemb plugins.
[08-23-2017 :: 19:31:53] [Quests] Unable to read perl file 'plugin.pl'