Postgres keep alive configuration

Hi,

I try to configure these 3 parameters to activate keep alive on a sever
Postgres in version 14.

tcp_keepalives_idle = 3
tcp_keepalives_interval = 2
tcp_keepalives_count = 30

After issuing alter system set ... command and a pg_reload_conf(); these
parameters keep value 0.

I also check these OS parameters
grep TCP_KEEPIDLE /usr/include/netinet/tcp.h
#define TCP_KEEPIDLE 4 /* Start keeplives after this period */

grep TCP_KEEPINTVL /usr/include/netinet/tcp.h
#define TCP_KEEPINTVL 5 /* Interval between keepalives */

grep TCP_KEEPCNT /usr/include/netinet/tcp.h
#define TCP_KEEPCNT 6 /* Number of keepalives before death */

and

sysctl net.ipv4.tcp_keepalive_time
net.ipv4.tcp_keepalive_time = 7200

Thanks for helping on this point

Fabrice