If you need more ports, then you can plug an Ethernet switch into one of the Ethernet ports of the mini connector.
If you need better wireless coverage, then you simply plug in a wireless access point into a spare port.
And specifically this post https://community.bt.com/t5/BT-Devices/Wi-Fi-extender-compatibility/m-p/1870295#M5351
Where would I obtain wireless access points?
Plenty of places, Amazon is one. This link on my website has the setup info.