Smash bros error code 001-0502

For some reason I can't play smash online and have had this problem for over a year. I can't play smash, pokemon y nor pokemon OR but the e-shop and mario kart work fine. I have tried everything and have tried multiple times. I tried static IP, DMZ, allowing mac address, turning of my firewall and multiple reboots. Some days I can get on but usually get kicked off after about 3 minutes on all the games I mentioned. I think the problem has something to do with my router setting because I only started having this problem when I switched ISPs and it works fine when I am connected to somebody else's wifi. Calling nintendo is not an option because I live outside of the US. Any help would be appreciated.