Any news? I've got the same issue also .... RB951 Upgraded to 6.40.9 two weeks ago (was attacked by mining scrypt), next days logon was successful, last successful connect was Sep 11, but now "Wrong user or password .." Tried Winbox 3.11, 3.14, 3.18 - all negative. Unfortunately - all imp...

I had update my RB951Ui-2HnD to ver. 6.42.7, and now not login "ERROR: wrong username or password".
Winbox 3.18 ver. not solved issue.