NME fails with "ERROR: [4951-33-9-00000A07] Unable to migrate message" (4331636)

When migrating user data, Notes Migrator for Exchange (NME) encounters the following error:

23:01:44 ERROR: [4951-33-9-00000A07]Unable to migrate message: Note ID 000057FA
23:01:44 NSFNoteOpen[Ext]:
23:01:44 Network operation did not complete in a reasonable amount of time; please retry

As a result, the message referenced in the error is not migrated.

The NME console is losing connectivity to the Domino server during the data migration.

This requires network troubleshooting as the migration console is not able to keep a continuous connection to the Domino server. The local OS Event Viewer or network monitoring software may be helpful to determine possible issues.