MongoDB cursor read timing out

Question

I'm using MongoDB 5.0 with version 4.5 of the Java driver.

I have an operation that reads data from a cursor. This cursor may return a large number of results (sometimes over a million). It's been working for a while, but lately I've been experiencing socket timeout errors while reading from the cursor.

    MongoCursor<Document> iter = collection.find(query)
                .batchSize(50)
                .projection(projection)
                .iterator();

Then I just call hasNext() and getNext() in a loop, sending the results elsewhere. Eventually, this happens:

com.mongodb.MongoSocketReadTimeoutException: Timeout while receiving message
        at com.mongodb.internal.connection.InternalStreamConnection.translateReadException(InternalStreamConnection.java:630)
        at com.mongodb.internal.connection.InternalStreamConnection.receiveMessageWithAdditionalTimeout(InternalStreamConnection.java:515)
        at com.mongodb.internal.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:355)
        at com.mongodb.internal.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:279)
        at com.mongodb.internal.connection.UsageTrackingInternalConnection.sendAndReceive(UsageTrackingInternalConnection.java:100)
        at com.mongodb.internal.connection.DefaultConnectionPool$PooledConnection.sendAndReceive(DefaultConnectionPool.java:490)
        at com.mongodb.internal.connection.CommandProtocolImpl.execute(CommandProtocolImpl.java:71)
        at com.mongodb.internal.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:253)
        at com.mongodb.internal.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:202)
        at com.mongodb.internal.connection.DefaultServerConnection.command(DefaultServerConnection.java:118)
        at com.mongodb.internal.connection.DefaultServerConnection.command(DefaultServerConnection.java:110)
        at com.mongodb.internal.operation.QueryBatchCursor.getMore(QueryBatchCursor.java:268)
        at com.mongodb.internal.operation.QueryBatchCursor.hasNext(QueryBatchCursor.java:141)
        at com.mongodb.client.internal.MongoBatchCursorAdapter.hasNext(MongoBatchCursorAdapter.java:54)
        [.... private code ....]
Caused by: java.net.SocketTimeoutException: Read timed out
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
        at java.net.SocketInputStream.read(SocketInputStream.java:171)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)
        at sun.security.ssl.SSLSocketInputRecord.read(SSLSocketInputRecord.java:464)
        at sun.security.ssl.SSLSocketInputRecord.bytesInCompletePacket(SSLSocketInputRecord.java:68)
        at sun.security.ssl.SSLSocketImpl.readApplicationRecord(SSLSocketImpl.java:1341)
        at sun.security.ssl.SSLSocketImpl.access$300(SSLSocketImpl.java:73)
        at sun.security.ssl.SSLSocketImpl$AppInputStream.read(SSLSocketImpl.java:957)
        at com.mongodb.internal.connection.SocketStream.read(SocketStream.java:109)
        at com.mongodb.internal.connection.SocketStream.read(SocketStream.java:131)
        at com.mongodb.internal.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:647)
        at com.mongodb.internal.connection.InternalStreamConnection.receiveMessageWithAdditionalTimeout(InternalStreamConnection.java:512)

This error happens consistently on two particular queries, and nowhere else. I've been using these queries for a while, and the queries haven't changed, but the data that they return is constantly changing. What are some possible reasons for the queries to start failing now?

Could I be hitting some sort of operation time limit on the server? I see a maxTime() option in the client code - but I can't find any information on what the default is. Is the above error consistent with what you'd see when you hit this limit?