G'day

I have just gotten a new Computer with a TP-Link PCIe wifi card installed. For the first week I was unable to connect to a network, then I could connect to a network but there was no internet access. Currently, I can connect and there is internet access but it is horrendously slow and unstable. My macbook laptop right next to the computer and on the same network has more than 10 times of the internet speed my PC is recieving. I have tried everything from restarting the computer, resetting network settings, runnings commands, uninstalling/resetting/updating drivers. It has become very frustrating, please help