Unable bring back working mongo cluster, after ops manager removal

Hello, I need help in returning mongodb cluster to working state.
I had an ops manager deployed with manager enterprise operator and a cluster created via the same operator. After necessary reinstallation of ops manager, I am unable to connect working sharded cluster to mongos. Mongos itself tells that:
“SASL SCRAM-SHA-1 authentication failed for mms-automation-agent on admin from client ; BadValue: SCRAM-SHA-1 authentication is disabled”}"
Anyone has some ideas?