It appears that your computers obtains a public ip address from your service provider. Filemaker dosen't have a way to specifiy the ip address, it is obtained automatically. Apparently it is setting 123.xxx. as the Ip address. You can contact your service provider to obtain a static ip address, or a persistence ip address. Or you can get a router which assigns local ip addresses to the local network, and the router will be assigned the public ip address.
So it really need a router for this to work....
But it's just so odd since in filemaker network setting it shows TCP /IP Address: 192.168.x.x when I'm not connect to internet just in my office network. And my clients can see this host PC 192.168.x.x in their open remote dialogue under local hosts tab but can see the file and can't open it. It's strange that filemaker can show this internal IP but can't open file on it.
And it's also strange that I have to publish to web to be able to open remote on clients with external IP. Without publish to web the clients still get nothing.
Thanks a lot for helping. I really appreciate it.