Hi Mark,
This is by design. The FX30 and FX30S is purposefully shipped with the firewall highly secure. Every customer’s needs are different, so you will need to add specific firewall rules to suit your custom needs.
You’ll need a rule like this:
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
But you’ll need to ensure you add it before the rmnet_data0 DROP rule. The rules are located at: /etc/iptables.rules