I am using M0 for testing but we are having the same issue from M30.
the instance and problem from peering is not. This error starting after some weeks we deploy our first lambda.
When we deployed our first lambda functions. everything was working good THEN after some weeks, this issues start to appears. No reason and I can find explainiation of why. SOMETIMES it connect to intance M30 and other time NOT.
This is a seriues issue that is putting our business in risk be cause we can not connect with Mongo Atlas. this is terrible!
we need to fix this AS SOON AS POSIBLE
I found that many other users have been having same issues but NO response of why that is happening: even the post doesnt seems that have a solution