Adding new Slave to existing Mongo cause the Timeout in Application

Hi,

We are having 2.7TB of data on primary and due to some reason secondary went down and it is now completely out of sync. So now whenever it is getting added into cluster my application starts timing out. Also since slave sync from the beginning it takes almost 2 to 3 days to fully in sync with master.

For application we tried to check if there is issue with write concern but it shows w:1.

Is there is any way we can add Replica without application timeout. Because all operations on master starts timing out as soon as we add Replica. Once replica is in sync we don’t see such issues.

MongoDB Version is 4.2 community version