Also, our office will not sell them. BUT there is a problem in what you wrote.
"moving the extender as close as possible" is incorrect. They tell you it goes midway.
Link: https://kb.netgear.com/25508/Where-should-I-place-my-NETGEAR-Wi-Fi-range-extender
That said the NANO USB adapter is not that long range. Try another with an antenna since what you have almost worked.
Also, I've solved such with Powerline WiFi units like: https://www.amazon.com/TP-Link-AV600-Powerline-WiFi-Extender/dp/B00HSQAIQU/
I have a detached garage at my apartment (non line of sight) that I want to connect to my network. The signal quality is poor, however I have successfully connected a raspberry pi with a TP-link N150 USB wireless adapter to my wifi network. I can communicate with the device, although the connection is slow. I have been trying to connect a TP-Link AC1750 wifi range extender, but despite repeated attempts and moving the extender as close as possible, I can't get a connection. A wired network connection is not possible. My question is, why would a small low power USB wifi adapter be able to connect to my wifi network when an AC1750 range extender can't?

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