Until today, I am still unable to play any online multiplayer mode since launch day. The only mode i could play was mobile hacking.
During the first weeks (before the recent patch), I was constantly faced with the very popular NAT Error, so I tried the following fixes:
1. check UPnP on router (which was already turned on)
2. Check firewall whitelist on router and windows (for both Uplay and W_D) - ended up disabling them still didn't work
3. put PC on DMZ
4. port forwarding
5. disabled and unistalled VMware and Hamachi. (I was left with only 1 network adater - LAN)
6. set Nat_transversal to 0
7. disabled use of proxy on Uplay settings.
But after much effort, none of them fixed the game for me.
****AFTER PATCH*****
I kept the settings said before, then tried to play again, still no luck and this time, it was giving me an error that Ubisoft Servers are no longer available. I found a fix to remove that error, just turn back nat_transversal back to 1 from 0, and the error goes away, but the original NAT problem comes back.
So yeah, now I am literally stuck here waiting and google-ing my ass off. I hope someone can help me here =)
********TL;DR - I am unable to play online before patch because of NAT problem, and still after the patch, after trying every single possible solution posted on the internet.