@Sunshine

Thank you for your reply. It now does seem to be the case.

I tried plugging the adapter directly into the router and the extender in my living room, they worked flawlessly together. It wasn't until I plugged the extender back in the garage that it worked for a short moment but the pairing LED indicator soon disappeared again and there was no internet connection.

I've now plugged it into an outside socket and the signal reaches my garage which is also working flawlessly, however, whether this is feasible long term due to it being outside despite being in a protected cover, I don't know.

Would you know what the contributing factors could be for the extender not working in my garage and if there's any setting or adjustment that would remedy it?

Thanks very much.