I'm using Azureus lately to do Bittorrent download, and for those that have used Azureus before, you should be pretty faimilar with these 2 icons :

and

.
I never get a

before since I started to use Azureus because I don't have "total control" of the router in the place where I stay previously. The previous housemates who own the router are just too scared to touch the router settings and hence, tweaking the router to speed up BT downloading is a forbidden area.
Well, I always thought that their reason is so funny... but, now I think that's reasonable because I just messed up the router's settings in the new place I stay right now and crippled the internet connection... lol... that sucks because obviously it's not my fault. The Belkin router is rebooted after I changed the settings, that's normal... but it's not when some of the WAN settings are lost after rebooting ! I was like.. OMG! this router is crap... how can the router make such stupid mistake ?
Everything is too late. So I have to ran to a place that has internet connection, searched for the ISP's DNS IP address and other settings info. The lucky thing is that, the username and password is still saved in the router. The router finally works after several dozens of rebooting. My piece of advise ? Remember your settings before rebooting your router ! I know information should not be deleted/lost after a rebooting process... but shit happens ! so watch out =)
Now instead of
NAT Error, I have

after configured the port forwarding thing. Download speed is significantly boosted by at least twice. So if you still have NAT problem, you should really configure your router... it really speeds you up =)