> I've tried all those tips, still no improvement though.

Just in case "those tips" refer to my six links above: They are a reply to what amigadave wrote (that's why I quoted him in that posting), not to your problem, so it's not surprising that they are of no help for you.

> Is there any chance [...] wifi will be useable on the mini?

Not with MorphOS 3.0 and the Mini's built-in WiFi I'm afraid.