RAX200 - Restricting Port Access to external IP Range

Apologies for a long preamble on this.

Problem: I have a streaming camera which works. I can see it on my home network all the time. I use a streaming service based in the USA, and I can embed the stream in various websites using the RTSP address.

The streaming service requires ports 80 and 554 to be open. I have two rules which do that on the RAX200. And I emphasise, everything works.

However, for the last two years, I have been pulling my hair out over an issue where the ports suddenly close - between 2-10 times a day. Until recently, and after trying everything I could think of, I had concluded the only way to re-open them was to reboot the router. That always opened them, but it is not a good solution.

After speaking with my streaming host, they asked if the ports ever re-opened by themselves. I had never looked into that, but over the last three days I have discovered that they do re-open - anywhere from 30-60 minutes after they close. This is obviously a major issue, as my stream is down for up to five hours a day. So I looked into it further.

I found that when the ports were apparently closed (using an online port scanner), netstat informed me that they were actually still 'listening' - which I believe means they are open.

I had been suspicious of Netgear Armor in this, and that was now the prime suspect. When I disabled it in the middle of that down period, the ports immediately appeared open and have not closed down since. So right now, Armor is almost certainly the problem.

My streaming host has suggested I lock down the ports and restrict access to only their IP range, which may stop Armor being triggered to do what it is doing.

Question: How the heck do you restrict external access to a port to a range if IP addresses on the RAX200?

There are no firewall settings, which is where you'd do it on cheaper/older routers.

I'd appreciate any suggestions.

Thanks