Inconsistent core behavior

Hi, the server where I play recently changed his host, and now, the core behaves really weird,
for example, today I was walking on Shadowmoon Valley and won the achievement for explore borean tundra…
a lot of players are complaining about getting client crashes, one raid won Herald of the titans achievement whithout meeting the requirement too,
and probably a lot of other things that i didn’t see yet.

The core is the same used in the old host, which doesn’t had these kind of problems, so I think this is most likely some linux config,

So i’m wondering if anyone have experienced that before and know what causes it and how to solve.

Core revision is at

We have about 600-1300 players online, and restart the worldserver daily
I can ask my admin for more info if needed.