Ok, so you're getting a private address. Now use that tcpdump command to see if anything comes in on those ports. Also try to open other (higher numbered) ports, you can forward those to any port on your fbsd machine. Something like <external ip>, port 2222 to <fbsd>, port 22. Make use of tcpdump, learn how to use it. It's an invaluable tool to solve all sorts of network issues.
If nothing comes in it's either the router or you have a very strict ISP. Netgear usually has all their manuals for download on their site, in case you can't find it. Perhaps a firmware upgrade is available that allows more features.