To get the Oracle Client IP address , you must use the one you suggested:
select sys_context('userenv','ip_address')
from dual;
To get the IP address of Oracle Server , you can use:
select utl_inaddr.get_host_address(sys_context('userenv','server_host'))
from dual;
( ):. IP- , , . ? . IP- -. Oracle Appex 100% PLSQL, .