@terziyski again, thanks for trying but your posts in this discussion are not helpful at all. If someone else has experience with a similar problem, any advice appart of saying how it's not possible...

@terziyski thanks but as I've mentioned in the OP, the router is in used condition, this means it wasn't provided by my ISP. The person I got it from unfortunately also doesn't remember the password....

I have got a used TP Link EC230-G1 Router. Everything works fine but I am not able to get into the router as I do not know the password. Even after a successfull hard reset (holding the reset button...