^must be your isp setting or something because my internet by default from my isp set me to 2.4ghz from the start, in fact i cant set it to 5ghz because the moment i switch to that my internet just stop working/dead.

right now iam using the "open port" method and so far i didnt get error 90002 yet after 2 dungeon run, my latest record is 3 dungeon run before the 4th one i finally get the 90002 again.