The Error log is here:
2020-11-01 12:25:34.275 WARN 20242 --- [nio-8088-exec-1] org.mongodb.driver.connection : Got socket exception on connection [connectionId{localValue:4, serverValue:114406}] to cluster0-shard-00-02.1c6kg.mongodb.net:27017. All connections to cluster0-shard-00-02.1c6kg.mongodb.net:27017 will be closed.
2020-11-01 12:25:34.283 INFO 20242 --- [nio-8088-exec-1] org.mongodb.driver.connection : Closed connection [connectionId{localValue:4, serverValue:114406}] to cluster0-shard-00-02.1c6kg.mongodb.net:27017 because there was a socket exception raised by this connection.
2020-11-01 12:25:34.295 INFO 20242 --- [nio-8088-exec-1] org.mongodb.driver.cluster : No server chosen by WritableServerSelector from cluster description ClusterDescription{type=REPLICA_SET, connectionMode=MULTIPLE, serverDescriptions=[ServerDescription{address=cluster0-shard-00-00.1c6kg.mongodb.net:27017, type=REPLICA_SET_SECONDARY, state=CONNECTED, ok=true, minWireVersion=0, maxWireVersion=8, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=46076648, setName='atlas-d9ovwb-shard-0', canonicalAddress=cluster0-shard-00-00.1c6kg.mongodb.net:27017, hosts=[cluster0-shard-00-00.1c6kg.mongodb.net:27017, cluster0-shard-00-01.1c6kg.mongodb.net:27017, cluster0-shard-00-02.1c6kg.mongodb.net:27017], passives=[], arbiters=[], primary='cluster0-shard-00-02.1c6kg.mongodb.net:27017', tagSet=TagSet{[Tag{name='nodeType', value='ELECTABLE'}, Tag{name='provider', value='AWS'}, Tag{name='region', value='US_WEST_2'}, Tag{name='workloadType', value='OPERATIONAL'}]}, electionId=null, setVersion=1, lastWriteDate=Sun Nov 01 12:25:29 PST 2020, lastUpdateTimeNanos=104428017411386}, ServerDescription{address=cluster0-shard-00-02.1c6kg.mongodb.net:27017, type=UNKNOWN, state=CONNECTING}, ServerDescription{address=cluster0-shard-00-01.1c6kg.mongodb.net:27017, type=REPLICA_SET_SECONDARY, state=CONNECTED, ok=true, minWireVersion=0, maxWireVersion=8, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=41202444, setName='atlas-d9ovwb-shard-0', canonicalAddress=cluster0-shard-00-01.1c6kg.mongodb.net:27017, hosts=[cluster0-shard-00-00.1c6kg.mongodb.net:27017, cluster0-shard-00-01.1c6kg.mongodb.net:27017, cluster0-shard-00-02.1c6kg.mongodb.net:27017], passives=[], arbiters=[], primary='cluster0-shard-00-02.1c6kg.mongodb.net:27017', tagSet=TagSet{[Tag{name='nodeType', value='ELECTABLE'}, Tag{name='provider', value='AWS'}, Tag{name='region', value='US_WEST_2'}, Tag{name='workloadType', value='OPERATIONAL'}]}, electionId=null, setVersion=1, lastWriteDate=Sun Nov 01 12:25:29 PST 2020, lastUpdateTimeNanos=104428010234368}]}. Waiting for 30000 ms before timing out
2020-11-01 12:25:34.316 INFO 20242 --- [ngodb.net:27017] org.mongodb.driver.cluster : Discovered replica set primary cluster0-shard-00-02.1c6kg.mongodb.net:27017
2020-11-01 12:25:34.612 INFO 20242 --- [nio-8088-exec-1] org.mongodb.driver.connection : Opened connection [connectionId{localValue:5, serverValue:108547}] to cluster0-shard-00-02.1c6kg.mongodb.net:27017
2020-11-01 12:25:34.838 WARN 20242 --- [nio-8088-exec-1] org.mongodb.driver.connection : Got socket exception on connection [connectionId{localValue:5, serverValue:108547}] to cluster0-shard-00-02.1c6kg.mongodb.net:27017. All connections to cluster0-shard-00-02.1c6kg.mongodb.net:27017 will be closed.
2020-11-01 12:25:34.838 INFO 20242 --- [nio-8088-exec-1] org.mongodb.driver.connection : Closed connection [connectionId{localValue:5, serverValue:108547}] to cluster0-shard-00-02.1c6kg.mongodb.net:27017 because there was a socket exception raised by this connection.
2020-11-01 12:25:34.876 INFO 20242 --- [ngodb.net:27017] org.mongodb.driver.cluster : Discovered replica set primary cluster0-shard-00-02.1c6kg.mongodb.net:27017
2020-11-01 12:25:34.878 ERROR 20242 --- [nio-8088-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.data.mongodb.UncategorizedMongoDbException: Exception sending message; nested exception is com.mongodb.MongoSocketWriteException: Exception sending message] with root cause