em vao duong link nay xem:
http://support.automation.siemens.co...ew/en/26662448
Doc file tên "VPN Connections with standard DSL Routers (Gateway / Gateway and Gateway / Clien
t) (English) ", nó huong dan dung DynDNS - 1 dịch vụ thay the cho viec dung IP tĩnh.