Hi Rodrigo,
Happy New Year!
Version using 4.2.8
Our all mongos suddenly stopped working, unable to connect and we were receiving constantly these messages:
NETWORK [conn1524750] DBException handling request, closing client connection: ClientDisconnect: operation was interrupted.
and
SHARDING [PeriodicShardedIndexConsistencyChecker] Attempt 0 to check index consistency for DBname.Collname received StaleShardVersion error :: caused by :: StaleConfig
We logged these jira, but we are not sure if this is required flushrouter config or some hmac key refresh issue.
https://jira.mongodb.org/browse/SERVER-53540
So after some digging, I found these articles that stated flush required, because sometime metadata did not get updated across all the cluster.
https://docs.mongodb.com/manual/tutorial/troubleshoot-sharded-clusters/#cursor-fails-because-of-stale-config-data
https://docs.mongodb.com/manual/reference/command/flushRouterConfig/#considerations
But we did not have any of the drop database and other conditions except getShardDistribution commands.