Weird,
> use nodebb
switched to db nodebb
> db.objects.update({ _key: "config" }, { $set: { "maintenanceMode": 1 } });
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
NodeBB restart.
It's working, checked APC and the switch is turned on.
I think i was loged in as administrator before, but i was checking maintenance page in APC and switch was turned off.