In my experience, I've been able to toggle QOS on or off without breaking any existing "normal" connections. That's great. In my case, I have a custom iptables rule to change the port number on a specific outgoing connection, so I can treat a service running on a non-standard port as if it is running on the standard port. So I have something like this in my firewall script tab. Code: iptables -t nat -A PREROUTING -d 220.127.116.11 -p tcp --dport 445 -j DNAT --to-destination 18.104.22.168:9445 iptables -t nat -A PREROUTING -d 22.214.171.124 -p udp --dport 445 -j DNAT --to-destination 126.96.36.199:9445 However, toggling QOS seems to break existing connections that rely on this rule. (New ones can be established, of course, but it disrupts anything in progress). Can I save these rules somewhere else so that they are treated more like the other rules, and stay intact through a QOS toggle? For example, in /etc/iptables or a shell script somewhere that modifies that config file before the service is restarted? I'm running Shibby's build.