ECM can't work on WP7601-1


I am doing some tests with WP7601-1 CAT1 module.
I successful setup it to connect to callbox with PPP.

I am trying setup it with ECM now, but I can’t make it work.
The firmware on my module is ‘SWI9X07Y_02.06.02.00 000000 jenkins 2017/08/05 01:02:55’.
Per info show on callbox, I seeing my WP7601-1 is connected, and confirm it gets IP from callbox by AT+CGADDR
I connect a host behind WP7601-1. The host get IP 192.168.225.xx from module and set gateway to
I can ping to from host, but can’t access to
It seems that there is a NAT gateway in WP7601-1, but it doesn’t works as expected.
Could someone please give me some suggestion for address the issue?