would blocking these url's just block the wii U end or botht he 3ds end too? prolly a stupid question but better safe than sorry.
It will block Wii, WiiU and 3DS.
Servers might differ from user to user.
Here is what I noticed:
nus.cdn.shop.wii.com : seems to be used by Wii and WiiU, based on wiimpersonator log
nus.cdn.wup.shop.nintendo.net : the server I'm connected to when updated my WiiU
nus.c.shop.nintendowifi.net :
nus.cdn.c.shop.nintendowifi.net : the server I'm connected to when updating my 3DS
nus.wup.shop.nintendo.net : Main URL to check if servers are available. Blocking this URL alone should block all eshop access (eshop and updates)
ccs.wup.shop.nintendo.net : blocking this URL is also blocking updates
Blocking only nus.cdn subdomain without blocking the others has strange result.
the console downloads all the update files, but is probably storing the HTTP answer inside ("403 forbidden"). after download it tries to install and fail. On next boot it deletes the files.
It might allow access to eshop without allow updating. though, it seems like it's updating so it might be frightening or not recommended to download fake file content.