D link not working.

MJULK07, in this case I can suggest to contact D-Link technical support, because this forum about Xbox and network related problems, so please use this link:
http://support.dlink.com/

Try a hard reset of the xbox hold the home button for 8 seconds till it completely shuts off and unplug the xbox for 5 minutes then forget your network and try reconnecting

Make sure Xbox Live is fully supported in your country: http://www.xbox.com/live/countries

Microsoft is aware of this problem with this sign-in error in most middle-Eastern countries and are working to fix it.

If your country isn't listed here, then I am afraid there is no workaround for this.

Let's just hope this will be resolved so that unsupported countries can access the Xbox services.

Greetings GRUBE!

Can you also tell us why you need to configure port forwarding for Xbox traffic.

Heya GRUB HE4D!

Sorry to hear you're having trouble with connecting to Xbox Live after setting up your new router. So we can help narrow this down, do you get an error message or anything like that when you try to sign into Xbox Live?

If you're not getting a particular error message or error code, run an Xbox Live Connection Test and run through this guide for

Xbox 360 Connection errors. It should correlate with where the red X shows up for you after the test.Let us know how it goes!