Hello,
The application we are developing will be using Square Terminals to handle physical payments, but the locations are most likely in areas with low to none WiFi signal service. However, there will be a computer next to it with Ethernet connection to the internet. Is it possible to connect over Bluetooth or any other technology than WiFi?
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Based on the information you’ve provided, the following documentation will help answer your question:
Terminal API Requirements
Use the Point of Sale API in Offline Mode
Build on iOS: Point of Sale API
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Dear bot, this contains, as always, not a solution.
If there’s a computer next to the device that’s connected to ethernet you can connect to the Terminal via ethernet. You’ll probably need a switch for the extra ports. 
Do you mean we should use this device: Hub for Square Terminal | Square Shop ?
Yes, you’ll need to use that and an ethernet switch to have the computer connected along with the Terminal.
Thank you very much, Bryan. I was able to pay over an Ethernet connection the way you described it.