I want to configure a firewall rule, that blocks the traffic from a specific ip address (192.168.31.120) to the wan. But only when the RUT955 is connected to the internet trough the interface MOB1S1A1 (SIM Card).
I tried to make a costom rule. First I tried to block all traffic from 192.168.31.120. But I already failed with that. When I saved the costom rule (Network > Firewall > Costom Rules) all devices no longer have internet access.
iptables -A FORWARD -s 192.168.31.120 -j DROP
This is the only rule I added. After I press reset all devices can connect to the internet again.
Can you help me to find the error? And what do I have to add, that only the traffic trough the interface MOB1S1A1 will be blocked?