How to correctly monitor a Database Oracle

Hi, Jorge. I am facing the same issue even with your string. (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=%node_ip%)(PORT=%node_port%)) (CONNECT_DATA=(SID=PRODM1)(SERVER=DEDICATED))).

I am suspecting that, 1. We have three VIP for Oracle Servers and It's causing the disruption with conflict. 2. Firewall Port for 1521 is not Open, Do we need to Open Daemon Port 1521 for the Communication? Because, we have everything setup at 1590 and I see both 1521 and 1590 Ports for traffic.

Please suggest me something. I need to Resolve this issue in 1 week before we go live..