Huawei HG612 - Routing/Firewall
Routing and firewall
From the drop-down menu, choose Firewall level: BT, select the Delete level function and left-click on Submit.
Now choose Firewall level: Custom, enter a descriptive name into blank field and left-click on Submit.
Select the IP filtering option and define two rules. The first, From-LAN, to allow all connections that originate on the LAN-side of the firewall access to the WAN-side. The second, From-WAN, to disable all connections that originate on the WAN-side of the firewall access to the LAN-side. Left-click on Submit.