isc_arg_gds          isc_network_error (335544721)
isc_arg_string       "сервер"
isc_arg_gds          isc_net_lookup_err (335544704)
isc_arg_gds          isc_host_unknown (335544706)

SQL> connect localhost:aaa;
Statement failed, SQLSTATE = 08006
Unable to complete network request to host "localhost".
-Failed to establish a connection.  <<<==== вот это и есть isc_net_connect_err
SQL> connect localh:aaa;
Statement failed, SQLSTATE = 08006
Unable to complete network request to host "localh".
-Failed to locate host machine.
-The specified name was not found in the hosts file or Domain Name Services.