You just have to set up a goal system. I bet a modified quest line that works like a regular job for a character and lets the players become a junior guard would work. Then you can send them on regular directed hunts that gradually build up to higher strength mobs. It always surprises me but it seems to hold true for most players, the game has to tell them what to do or they won't figure out what to do or will lose interest in doing.
You just have to set up a goal system. I bet a modified quest line that works like a regular job for a character and lets the players become a junior guard would work. Then you can send them on regular directed hunts that gradually build up to higher strength mobs. It always surprises me but it seems to hold true for most players, the game has to tell them what to do or they won't figure out what to do or will lose interest in doing.
Not sure you have recently done some questing lately (in case I would be interested in hearing a feedback), however some quests including the tutorial are currently trying to focus the players on a "main theme": the stone labyrinth invasion.
This recursive treat is intended to be one of the main "world problems" to create tension in-game and keep the Yliakum society unitedo to some extend and - why not - create conflict as well (between PC and PC , between PC and NPCs, etc.).
Also many in game mechanics have been shaped that way in order to create that same feeling (there are recursive invasion of monsters coming from the bronze doors).
It could be the message and the goal is not clear enough, or hasn't been added in enough place to feel like enough of a threat for everyone. In case this can be fixed, more hints can be added in the quest and - why not - players can even propose more game mechanics around this (like more frequent invasions, repeatable invasion quests, etc.).
I'm sure many of this features can be added, given time.