AE Tax uses System Release on the workstation to connect to a service on the server called System Release DAL using TCP port 6606, System Release DAL then opens an ODBC connection to the Microsoft SQL Server instance.

The first query that it run on the database is to locate the TA record from the AETAX1 database.

If the workstation can’t connect to the System Release DAL at all, you will get a “TA is offline” error.

If the workstation can connect to System Release DAL, but can’t access the SQL Database, you will get a “TA not found” error.

The cause your “TA not found” error was probably because the SQL Server was restarted, which means that System Release DAL would need to be restarted to start the ODBC connection ODBC again.

GetQueuedCompletionStatus and 0×4d4 (ERROR_CONNECTION_ABORTED) “The network connection was aborted by the local system.” seems to happen for no reason except to fill up your event log, highly annoying. There would be something coming from the SQL server returning this error, which in turn is logged by the System Release DAL that is connected to the SQL Server.
Doing a bit of searching of these errors on Google suggests that it’s related to Winsock 2 in Windows, so I don’t know if it’s myobs fault or not.