Ports don't unmap

[benoitlahoz]

Hi and thank you for the great work.

I'm using nat-upnp-2 like in the example.
It works well and finds my router, then map local <-> public ports THE FIRST TIME I launch the server. But when it comes to unmapping, the gateway returns NaN and the ports aren't unmapped.
So, when I try to 'remap' public ports to different local ports it throws this error:

Error: Request failed: 500
at Error (native)
at needle.post.err (/home/map/www/map/node_modules/nat-upnp-2/lib/nat-upnp/device.js:140:23)
at done (/home/map/www/map/node_modules/needle/lib/needle.js:432:14)
at PassThrough. (/home/map/www/map/node_modules/needle/lib/needle.js:671:11)
at emitNone (events.js:91:20)
at PassThrough.emit (events.js:185:7)
at endReadableNT (_stream_readable.js:974:12)
at _combinedTickCallback (internal/process/next_tick.js:74:11)
at process._tickCallback (internal/process/next_tick.js:98:9)

Any tips on this would be highky appreciated!
Thank you!