The test jstests/sharding/add_shard_4.js is currently disabled in the sharding_csrs_continuous_config_stepdown suite because it fails when config server stepdowns occur during addShard execution.

Problem:

When continuous config server stepdowns are enabled, the addShard command can encounter retryable network errors (including HostUnreachable) if executed while the config server primary is stepping down. The test does not retry these errors, causing it to fail.

Impact:

• The test cannot run in suites with continuous config server stepdowns

• Reduced test coverage for the addShard command under stepdown conditions

Solution:

Make the test resilient to retryable network errors by:

1. Wrapping addShard calls in retry logic that handles retryable network errors (including HostUnreachable)
2. Ensuring the test retries addShard when it encounters transient network errors during config server stepdowns