Connection lost contact between Primary and Standby

ORA - 03135 : connection lost contact while shipping from Primary Server to Standby server [ID 739522.1]

Changes

There may be a firewall rule changed or the firewall is newly installed.

Cause

Mainly ORA-3135 occurs when the connection is broken because of underlying network issues.

In  this case, an intermediate firewall between primary and secondary server is altering the data inside the sqlnet packet.

The trace clearly shows that primary sends a data with and the firewall / intermediate network device is changing the hostname to IP address (possibly a rule set in the firewall).

Ivolve the firewall administration team to check whether the firewall /intermediate network device can be stopped from altering the sqlnet packet.