Even if you port forward yourself, your ISP may still block connections and keep your NAT Type from being considered "Open" if you were to test in Windows. At that point it's up to them if they'll change it.
DMZ wont work on consoles with technicolor and thomson's routers because they are good hardwares (sarcasm). I had the same trouble and the thing i did was assigning DMZ to my laptop, then downloading a program called mypublicwifi and shared my private ip and converted my laptop into an Access Point and it actually worked. Test it out