Check out Litcessory. They sell on Amazon.

I've used their short extenders for cut ends. Those connectors can be...persnickety, but they work. The ethernet adapters may be a cleaner option, and they work with the stock cable ends, and may be easier to setup (I don't have any experience with them):

https://www.amazon.com/Ethernet-Compatible-Nanoleaf-Essentials-Lightstrips/dp/B0BCWFMD86/