It seems the answer in this thread (Accessing Meteor production database) does not work anymore when you want to access a meteor production database in 2016. I want to acces
You are trying to connect to a database version 3.0 while your meteor mongo
command still use the version 2.6.7 of mongo
Try this workaround :
Then run this command (should work on osx, linux and windows when sed is installed):
mongo `meteor mongo --url XXX.meteor.com | sed 's/mongodb:\/\//-u /' | sed 's/:/ -p /' | sed 's/@/ /'`
Source: https://forums.meteor.com/t/meteor-mongo-xxx-meteor-com-giving-exception-login-failed-workaround/15289