PROBLEM:
Every 5.5 minutes, this shows up in the actlog
08/13/20 08:05:25 ANR1663E Open Server: Server OLDSERVER not defined
08/13/20 08:05:25 ANR1651E Server information for OLDSERVER is not available.
08/13/20 08:05:25 ANR4377E Session failure, target server OLDSERVER is not defined on the source server.
08/13/20 08:05:25 ANR1663E Open Server: Server OLDSERVER not defined
08/13/20 08:05:25 ANR1651E Server information for OLDSERVER is not available.
08/13/20 08:05:25 ANR4377E Session failure, target server OLDSERVER is not defined on the source server.
08/13/20 08:05:26 ANR1663E Open Server: Server OLDSERVER not defined
08/13/20 08:05:26 ANR1651E Server information for OLDSERVER is not available.
08/13/20 08:05:26 ANR4377E Session failure, target server OLDSERVER is not defined on the source server.
08/13/20 08:05:28 ANR1663E Open Server: Server OLDSERVER not defined
08/13/20 08:05:28 ANR1651E Server information for OLDSERVER is not available.
08/13/20 08:05:28 ANR4377E Session failure, target server OLDSERVER is not defined on the source server.
SOLUTION:
QUERY REPLSERVER shows the GUID
REMOVE REPLSERVER (GUID) to cause the errors to stop.