Mongorestore: Replication Oplog Window has gone below 1 hours

I am trying to import an archive using mongorestore. I have a MongoDB Atlas replica set with 3 nodes. I tried “/writeConcern=majority” and even “/writeConcern=3” but I keep getting a “Replication Oplog Window has gone below 1 hours” email warning. I have found Alert Replication Oplog Window has gone below 1 hours which gives two options. One is exactly to utilize “writeConcern”, while the other being increasing the cluster “oplog size” (which is something I want to avoid).

Why isn’t “writeConcern” working?

Any help is appreciated.