the password is caps sensitive, if you are using the default router password keep in mind, some stickers got the passwords in uppercase but in reality it's a lower case password or vice versa.. double check on that...
i suggest you to delete the wifi settings and try to setup again, making sure you are using the right password.
if the problem is firewall and port fowarding, i suggest you to ask some techie friend who knows well about this stuff, because every router is different
and it all depends on what you are trying to do...
about the party issue.. it can be your hdd, it can be that you got a bad copy... i can't help you much with this, (you may try to download a new copy into a thumb drive and check if the issue still happens, then you can rule out the problem is not from hdd or copy you own)
anyway, keep in mind, nintendo servers shutted down, it's no longuer possible to play games online (without using custom servers), and i think every nintendo wii service like the eshop shutted down..
and no, my dad doesn't work for nintendo, it's a reference to the kids in the internet who always claim they got an uncle (or other familiar) who works for "x multi billion dollar company" so they know more about said console\game\product than anyone else...
