I tested this issue using app2.js script that it is attached here. I do the following steps to reproduce the problem:

• Start the node script with the network interfaces of the ReplicaSet brougth up.
• Perform some requests in order to check that the script runs well.
• Take down all network interfaces of the ReplicaSet (ifdown), and perform again some requests. In this case, we have to capture an error.
• Wait some minutes.
• Bring up the network interfaces of the ReplicaSet and wait some seconds. Sometimes the script can perform the query, but other times the client cannot recovery the connection and you need to restart the script if you want to have a good connection again.