At the alert log, we received this error message on the production database for the 19c Data Guard.

The primary alert log file showed:

LGWR: Attempting destination LOG_ARCHIVE_DEST_2 network reconnect (16198)
LGWR: Destination LOG_ARCHIVE_DEST_2 network reconnect abandoned
Fri Jan 4 12:00:36 2023
Errors in file //bdump/.trc:
ORA-16198: Timeout incurred on internal channel during remote archival
LGWR: Network asynch I/O wait error 16198 log 2 service ‘(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1522)))(CONNECT_DATA=(SERVICE_NAME=)(INSTANCE_NAME=)(SERVER=dedicated)))’

After investigating the issue, we noticed that our network is too slow. We encountered this error when the primary database attempted to send a large logfile to the standby database.

The NET_TIMEOUT attribute in the LOG_ARCHIVE_DEST_2 at the primary database is either not set or set to a low value (such as 5-10 seconds), causing the LNS (Log Network Services) to be unable to complete the sending of redo blocks within the specified time.

To resolve this issue, you should increase the NET_TIMEOUT value in the LOG_ARCHIVE_DEST_2 at the primary database to at least 15 to 20 seconds, depending on the speed of your network.

In our specific case, we have already set the NET_TIMEOUT value in the LOG_ARCHIVE_DEST_2 at the primary database to 60 seconds.

ALTER SYSTEM SET LOG_ARCHIVE_DEST_2 SERVICE= LGWR SYNC DB_UNIQUE_NAME= NET_TIMEOUT=60 VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)

Reference:
Redo Transport Services fails with ORA-16198 when using SYNC (synchronous) mode (Doc ID 808469.1)