Question Laptop 50+ Mbps, Desktop 2Mbps

Aug 4, 2019
Hoping you can help me restore my sanity with this one

I built a desktop PC for my Dad which we originally setup via ethernet to a powerline adapter. We have had intermittent issues with the powerline, so I installed a wireless card a little while ago (TP-Link WN881ND). Problem is the speed has now dropped through the floor - download speed will show as around 2Mbps, and will occasionally randomly jump to 12-18 Mbps, but not for any stable period of time. Upload speed tends to hold at around 12-16Mbps regardless of the download speed.

I've tried a phone, chromebook and windows laptop in the same location, and all get over 50 Mbps download speed.
When the PC is plugged into the router via ethernet, speeds increase to 65-70 Mbps, but this requires a 20 metre long cable dangling around the house whch my parents are not keen on.

So I updated the drivers for the wireless card and motherboard, then started exploring in the network adapter settings. When I access the adapter properties via device manager and go to advanced, I can only select IEEE 802.11b, or IEEE 802.11b/g under wireless mode.

However, the device is registered in device manager as TP-Link Wireless N PCI Express Adapter.
When I check via command prompt, netsh wlan show drivers lists the supported radio types as 802.11n, 802.11g, 802.11b, so I don't know why I can't select 802.11n via network adapter settings, or if that would even solve the problem

Please help before I smash this thing