This usually isn’t actually a wrong password issue, even though the extender keeps saying that. With the TP-Link RE330 this happens quite often when the setup doesn’t fully “stick” or when there’s a mismatch in WiFi security settings. The password can be correct, but the extender still fails the connection handshake and just shows “incorrect password”. What usually helps is doing a full reset again (not just a reboot) and then setting it up from scratch. If your router is using WPA2/WPA3 mixed mode, try switching it temporarily to WPA2 only during setup, because that’s a common trigger for this exact issue. Also worth trying WPS if your router supports it, it often avoids these setup glitches completely. If it still refuses after a clean reset + WPA2 setup, then it’s probably either a firmware quirk or a faulty unit, but in most cases it’s just a compatibility/setup issue rather than the actual password.