Using a Mac Book Pro with a LAN

Apple sells a TB3 to Ethernet adapter: Thunderbolt to Gigabit Ethernet Adapter. They have a USB to Ethernet adapter: Apple USB Ethernet Adapter that can be connected using a TB3 to USB-A adapter (find one at Amazon.)

@Kappy, the Apple adapter is NOT Thunderbolt 3, it’s TB1/2 and will not connect directly to a newer Mac.

But, it WILL work with the OP’s not-newer 2015 MBP which has TB2.

https://www.apple.com/shop/product/HJKF2ZM/A/belkin-usb-c-to-gigabit-ethernet-adapter

If you bought in Jan 2015 you have a mid-2014 MBP (the ‘early 2015’ models came out in March 2015). Your Mac has Thunderbolt 2 ports, the Apple Thunderbolt to Gigabit Ethernet Adapter will work with your Mac (as would the other one Kappy linked, via a USB-A port.).