After upgrading to 6.27.x or above the following log message is report very frequently:
"LOG","00000","send dummy packet failed, sendto failed: No route to host",
Grepping the logs shows it is reported multiple times throughout the day:
$ grep -c "send dummy packet failed, sendto failed: No route to host" gpdb-2024-09-2*.csv
gpdb-2024-09-20_000000.csv:388999
gpdb-2024-09-21_000000.csv:278434
gpdb-2024-09-22_000000.csv:178032
gpdb-2024-09-23_000000.csv:209994
gpdb-2024-09-24_000000.csv:199163
gpdb-2024-09-25_000000.csv:244729
gpdb-2024-09-26_000000.csv:38878
gpdb-2024-09-26_021357.csv:39206
This is a known issue related to IPv6.
The recommended workaround is to hardware disable IPv6.
Note: Disabling IPv6 with kernel parameter "net.ipv6.conf.all.disable_ipv6=1" is not sufficient.
As root user modify GRUB and reboot the machine:
A code fix is currently being developed and will be released in a future version.