Extender password AC1200

Hi,

I've just purchased an AC1200 Dual Band Wifi Range Extender (Model EX6120) and am really struggling to get it set up.

The instructions in the Quick Start seem nice and clear i.e. to connect with WPS, press the WPS button on the extender, (within 2 minuntes) press the WPS buttion on router (Technicolor TG589vac), move extender to half way to 'dead' area and connect to new extended wifi network.

All of the is fine, but as soon as I try to add the WiFi Password for the extender, it says that it is incorrect. Agh!

I've triple checked the password and it is definitely correct and is the same password that I use to connect any devices (iphones, ipads etc) to the wifi network without problem. However, with the Netgear extender it continues to say that the password is incorrect.

I've had a look at the advice for similar problems in the Community, but haven't been able to find (or understand) anything to help with my problem. I'm afraid that I am not very IT literate, so very simple and clear advice would be greatly appreciated.

Thank you.

Alan