Invalid Data. External IP Address!

[Colorman]

So, I'm trying to set up a Minecraft server on the port 25565.

My model is CG3700EMR and when I try to add an external IP Adress it just comes up with the error "Invalid Data. External IP Adress!" I have no idea why this happens or what it means (sorry if I'm a bit of a technical noob).

I'm trying to set up port forwarding for the port 25565 with the internal IP being 192.168.0.XX. But when I try to put in any IP in the 'External IP' field it just comes up as an invalid. I've also tried finding my external IP using websites like IP chicken but the error is still there.

All computers on my network can join the server using my internal IP but computers online can't. Not with the IP's from IP chicken either. And no antiviruses or firewalls are blocking the connection. So I don't know what to do. Please help.

If any more information is needed I am happy to supply.

[antinode]

> My model is CG3700EMR [...]

   I don't see that model at http://netgear.com/support .  Also, a
firmware version can be helpful as well as the (actual) model number.

> [...] when I try to add an external IP Adress it just comes up with
> the error "Invalid Data. External IP Adress!"

   Where are you trying to "add an external IP Ad[d]ress"?

> NetgearError.png

   I see the error message, but not what you put in to cause it.  If
your Web form looks like mine (D7000), then the "Server IP Address" is
the LAN address of the local server, not any external IP address.
(Which is why that field is pre-populated with the right stuff for all
but the rightmost octet.)

> Not with the IP's from IP chicken either.

   There's more than one external IP address?

   What's the LAN IP address of this "Minecraft server" system?  That's
the target in the port-forwarding rule.  You don't need to specify the
external IP address.  The router already knows its own WAN/Internet
address (probably better than you).