Hi @Kevin_Meng,
I don’t have much experience with this sort of use case. We generally recommend that a mongo.Client be created with a set of credentials which will then be automatically applied to all of the connections it creates. I’m not sure what the server behavior is if an application attempts to manually authenticate connections.
Also, based on the authentication spec, the auth conversation for the SCRAM-SHA-256 mechanism uses saslStart and saslContinue commands, not the authenticate command, so it’s possible that the commands you’re sending are not in the format the server expects.
– Divjot