Hello,
at first, Wii U is absolutely amazing console! :-)
But now I have first problem and i hope the last...
Problem is with searching for opponents in wii sports club. Sometimes my wii u cant search opponent 10-15 times in a row, in category Everybody... :/ Thats really awful. And doesnt matter, if there is morning, day or night... My friends havent got this problem, they have 99/100 successful joins the game..
I tryed set static IP address on my wii u and then set this address to DMZ on my router. But there is still not working.. I hope I do it right. Sometimes is lucky time, i can play for example five games of ten... But now, I try to searching opponents about 40 minutes and nobody?! 
Yesterday I called with my internet provider and I asked him for set public IP address. So I have public address, but still no changes He told me that public Ip address is not necessary on 101% for playing online games, so there is no reason why is not working...
And my one knowledge. If the searching opponets is successful - there is ALWAYS in first three seconds in court with targets. I know that game isnt start in first three seconds, then definitely no. And second knowledge. I played about 50 online matchs but NEVER I had first serving, fortune??
Have you somebody any idea?? Router is Tp link WR740N.
Sorry for my english and thank you everybody for answers. THX!