Nintendo maintenance on Wii U and Nintendo 3DS devices are taking place today starting at 4 p.m. and 5 p.m. PST, respectively.
As a result, online play and rankings for Monster Hunter 3 Ultimate Pack Relay Tools, which allow you to play the Nintendo 3DS version of the game with other players online via a Wii U, as well as for the official Wii U version of Monster Hunter 3 Ultimate, will be affected until 5 p.m. PST.
After this, Nintendo is moving on to maintenance on 3DS services which will affect online play and rankings on both the Poke Transporter and the Pokemon Bank. This will come to an end at 6 p.m. PST.
Maintenance schedules can be found on Nintendo's official website.