Your other alternative is to change your certification to certify FarmManager using the NIP of your 192 address (requires setting the p-label to 1).
Typically, you'd want internal nodes like FarmManager on your 192 address, not exposed to the public, and only have your gateway/agent/download server on your world ip, as people need to connect to it (assuming you're not using a filter/proxy, which is pretty much a must for a real server).
If you're not familiar with certification stuff, there's a few good posts on the forums, I posted the complete format:
Long story short, 0x2001 checks the physical ip of the connection (which is why you'd normally want to bind all server modules to a specific adapter), and then the IP they send via the packet can be spoofed. However, the certification configuration will change which IP to check for the packet sent (WIP/NIP) but not the 0x2001 check (which is why you have to bind it in the first place).
Alternatively, you can solve the problem by proxying all your server modules through a custom program that binds to the correct network adapter and simply forwards the traffic. However, if you're going that route, you might as well implement a filter.
