Hmm, I have turned the firewall on the hybrid off, but that didn't help. I also can't completely turn the firewall of my real router off, but I *can* put a computer into a "DMZ" (Demilitarized zone, haha) I've tried this on my hybrid *and* on my computer, but still no luck ...
And, errr, I do have multiple ip's actually:
I'm using a static ip as my "external network card eth0" (the one from the real router, as I turned that DHCP-server off) and that IP address is the same one as on my internal network card...
Finally, somewhere I can contribute!!
If you're running through a hardware router your configuration should be something like this:
Router WAN IP (Internet), will be a public address like 206.13.31.11 either static (given to you by your ISP that never changes) or dynamic (WAN setting in the router will be set to DHCP and the number may change).
Router LAN IP (Your internal network): This will be a private address chosen by you (The default for most routers is something like 192.168.1.254.
Your Core/Hybrid External address can be either statically assigned by you or dynamically assigned by your router. In either case the number has to be on the 192.168.1.XXX subnet (or whatever the LAN IP subnet is on your router)
The Core/Hybrid Internal address will have to be on a DIFFERENT subnet as your router/core external interface. i.e. if your router is on 192.168.1.xxx then your Core internal address can be on 192.168.80.xxx (which is the default), anything other than 192.168.1.xxx.
Example of working configuration:
Router WAN: 206.13.31.11
Router LAN: 192.168.1.254
Core External: 192.168.1.1
Core Internal: 192.168.80.1
Example of Non-Working Configuration:
Router WAN: 206.13.31.11
Router LAN: 192.168.1.254
Core External: 192.168.1.1
Core Internal: 192.168.1.2
The Core's Internal and External interfaces have to be on different subnets or it will not function correctly.
IMPORTANT NOTE:
If you want to continue to use your router as a DHCP server then the Core/Hybrid and your MD's have to be on different PHYSICAL network than your router. Meaning the router plugs into the external interface on your Core only and can NOT be plugged into a switch that other computers/MD's will be plugged into. All of your computers/MD's will plug into a switch that the Core/Hybrid INTERNAL interface is plugged into. This configuration works well for instances when you have (like I do) a computer network that is unrelated to the Media network and you wish to keep them separate.
Now, for opening ports.
You have to do it in two places. For this example I'm going to use 192.168.1.1 as your Core/Hybrid External address and 192.168.80.1 as your Core/Hybrid Internal address.
In your router you go to Port Forwarding or Applications and Gaming, whatever your router calls it and forward whatever port you want to 192.168.1.1 (The Core external address).
Then on the core you setup a port forward for the same port to the address of the MD or computer you want, for instance 192.168.80.50
So traffic for say port 22 comes in from the internet to your router, the router will forward that to the Core, then the core forwards to the client.
One caveat is that the Core dynamically assigns IP addresses to the MD's so the number could change, particularly if you leave the MD off for a while. I don't know what the default lease time is for the Core's DHCP server, but it's usually something like 3 days. If the IP of the MD does change then you will have to change the destination address in the Core to point to the new address of the MD. No changes will need to be made to the router.
I hope this helped, I'll monitor this thread so if you have any questions post em here and I'll be happy to answer.