Spring with MongoDB - losing connection - mongodb

Question

I have Spring Boot application running on Kubernetes connected to Mongo database (deployed with Mongo Operator)
Sometimes - I can't see a pattern so far - the connection between Spring application & MongoDB breaks. After some time connection is restored but this may cause an error to the user.
Logs from application:
12:00:32.606 INFO org.mongodb.driver.connection : Closed connection [connectionId{localValue:3, serverValue:17292}] to kompas2mongo-0.kompas2mongo-svc.dev.svc.cluster.local:27017 because there was a socket exception raised by this connection.
12:00:32.607 INFO org.mongodb.driver.cluster : No server chosen by ReadPreferenceServerSelector{readPreference=primary} from cluster description ClusterDescription{type=UNKNOWN, connectionMode=SINGLE, serverDescriptions=[ServerDescription{address=kompas2mongo-0.kompas2mongo-svc.dev.svc.cluster.local:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketReadException: Prematurely reached end of stream}}]}. Waiting for 30000 ms before timing out
12:00:32.612 INFO org.mongodb.driver.cluster : Exception in monitor thread while connecting to server kompas2mongo-0.kompas2mongo-svc.dev.svc.cluster.local:27017
com.mongodb.MongoSocketOpenException: Exception opening socket
at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:70)
at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:143)
at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.lookupServerDescription(DefaultServerMonitor.java:188)
at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:144)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.net.ConnectException: Connection refused
at java.base/sun.nio.ch.Net.pollConnect(Native Method)
at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:589)
at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:542)
at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:597)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:333)
at java.base/java.net.Socket.connect(Socket.java:648)
at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:107)
at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:79)
at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:65)
... 4 common frames omitted
12:00:42.808 INFO org.mongodb.driver.cluster : Cluster description not yet available. Waiting for 30000 ms before timing out
12:01:02.612 ERROR o.a.c.c.C.[.[.[.[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [/api] threw exception [Request processing failed; nested exception is org.springframework.dao.DataAccessResourceFailureException: Prematurely reached end of stream; nested exception is com.mongodb.MongoSocketReadException: Prematurely reached end of stream] with root cause
com.mongodb.MongoSocketReadException: Prematurely reached end of stream
Logs from MongoDB:
2022-08-21T12:00:33.583Z INFO controllers/replica_set_controller.go:132 Reconciling MongoDB {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.583Z DEBUG controllers/replica_set_controller.go:134 Validating MongoDB.Spec {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.583Z DEBUG controllers/replica_set_controller.go:143 Ensuring the service exists {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.600Z INFO controllers/replica_set_controller.go:390 The service already exists... moving forward: services "kompas2mongo-svc" already exists {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.600Z INFO controllers/replica_set_controller.go:308 Creating/Updating AutomationConfig {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.628Z INFO agent/agent_readiness.go:52 All 1 Agents have reached Goal state {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.628Z INFO controllers/replica_set_controller.go:288 Creating/Updating StatefulSet {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.639Z DEBUG controllers/replica_set_controller.go:298 Ensuring StatefulSet is ready, with type: RollingUpdate {"ReplicaSet": "dev/kompas2mongo"}
2022-08-21T12:00:33.639Z INFO controllers/mongodb_status_options.go:110 ReplicaSet is not yet ready, retrying in 10 seconds
2022-08-21T12:00:34.612Z INFO controllers/replica_set_controller.go:132 Reconciling MongoDB {"ReplicaSet": "dev/kompas2mongo"}
Mongo is configured as a Replica Set and application.yaml looks like this:
spring.data.mongodb:
host: ${MONGO_HOST}
database: ${MONGO_DATABASE}
username: ${MONGO_USERNAME}
password: ${MONGO_PASSWORD}
In documentation there is different connection string for replica set. Could this be the issue? Or do you have other ideas?