WiFi and Bluetooth card upgrade

Sadly, your systems version of board doesn’t offer a newer board. BroadCom made this version of board with a surface connector

Unlike the newer Retina series (pre 2016) which uses an edge connector

While the latter versions of retina models offered a better WiFi/BT board you can’t use it.

So your system is stuck with the AirPort Extreme it came with: WiFi - 802.11n & Bluetooth - 4.0 internally.

Now lets look at your options! You do have a Gigabit Ethernet interface and you also have USB3 both offer powerful connection possibilities. Most people really don’t need on the road speed, its when working at a desk that we often need the higher throughput for accessing a NAS or File Server for files or backup.