I have replicated the issue once.
However, after removing the password in Network -> Wireless -> Wireless security tab, I started to connect. Even re - adding the same password, there were no 'failed login' messages. Then again, it might simply require a restart of the wireless interfaces.
Since, currently legacy firmware versions only receive critical security and bug fixes, is there any specific reason you use 06.09.2 instead of current RutOS?