WiFi - Do some Friend Codes not work for you?

[Tales]

I just installed a Belkin router (which IS compatible with the DSi, checked the part number on the Nintendo site) and I noticed that only some FCs work for me. I can connect with some people, but others disconnect when they try to enter my party and I disconnect when trying to enter theirs. It seems to work for Pokemon (lol don't make fun).

Did this ever happen to you? If so, do you have a Belkin router?

Looking for answers. Help! o.o

EDIT: I've tried to set it up to have a Static connection, Dynamic connection, WEP security, and even took off the Firewall.

I now have a Static connection.