ANSWER:

Example of the multiplayer menu while in Limited mode
There are several reasons why this could be happening:
You are not currently signed into the PlayStation Network (PSN) / Xbox Live
If you are already registered on the PlayStation Network or Xbox Live, your profile will automatically sign into the relevant service. If this is not the case, ensure that you are using the correct profile and that your console can connect to the Internet.
You have more than 99 friends on PSN
We have identified an issue connecting to the Ubisoft servers if your PSN account has more than 99 friends. We are currently working with Sony to resolve this issue. In the meantime, try reducing the number of friends on your friend list to 99 or fewer and try connecting again.
The Ubisoft servers are currently unavailable
It is possible that the servers are unavailable, this would automatically revert you to Limited mode. To see if the servers are back online simply select "Go Online", if this fails then you can check any of the resources below to see news about the server status.
Facebook | Twitter | Assassin's Creed
Please note, you will not automatically be put back into Online mode once connection to the servers has been restored. You will need to select Go Online to reconnect.