Forums Connection Issues invalid username

THank you so much for your help.
However, I don't think that your suggestion helps me
to solve this problem because it still doesnt work at all.
I tried a lot of times to change my username and did it.
But it still appears Closing Link: 0.0.0.0 (Invalid username [강석준23])..

It even cannot affect the previous username in the
bracket in the error message above. I tried to change it into munky as you suggested but the new username that I have tried to put does not appear at all. and the error message still appears in the same way above.
Now I am trying to contact operator of the Dankun. net
...I appreciate your help anyways..THanks