Place Ruijie Gateways behind Router on Port Forwarding

Hi, I have SQL server which normally place on one of the LAN port of my ISP router and work fine with port forwarding from router, I use port 3307, then I bought ruijie gateway and place it between router and server on Vlan 100. I can ping the gateway & the router IP from my server and can go to my SQL intranet but I cannot have the port forwarding worked from internet access. Do I need to set anything on the router? Like Dmz and forward all port to ruijie gateway first. What external IP in ruijie gateway port forwarding should be? Is WAN  external IP or my gateway external IP.
MY WAN : 99.99.99.99
My router IP : 192.168.20.1  255.255.255.0
My Gateway : 192.168.10.3 255.255.255.0 on fix IP WAN0 port
My Server : 192.168.100.20 255.255.255.0 on Port LAN2 (Vlan 100)
I Finish setup my LAN VLAN ACL FLOW CONTROL ... I Am on the stage that I can ping from any port vlan I want to server that I am allowed of. I can ping IP 192.168.20.1 from my server 192.168.100.20. I can run my SQL server from any vlan port on the gateway that I am allowed as per ACL.
For internet access to my server I still have no luck and I didn't know what's wrong with it.  Please help.

Dear Hartono Kafrawi,
Sorry for the late reply. It is advised to come Rita to start a live chat with me to further check this issue.
https://www.ruijienetworks.com/rita

Looking forward to your visit