Thanks for the assistance @ben It is much appreciated. I have done a lot of experimentation the past while, (without success, though). To answer your questions: (1) The mongo instance is not a replica set. (2) It seems that it might not be related to moving to https. After removing the SSL Certificate to test, Dremio still did not want to connect to MongoDB. (although client apps such as MongoChef (Robo 3T) and noSQLBooster for MongoDB, connects without problems from the same environment)
I see in this thread in the Dremio Community Forum: Percona Mongodb 4.0.9-4 null pointer that Mongodb 4 is not supported yet by Dremio? Our issue might be related to this? (We cannot move back to MongoDB 3 though) What is the approx roadmap for Mongodb 4 support and what is the approx time-frames for moving the MongoDB connector out of Beta?
Thanks!