Need WiFi Advice

[#1]

I upgraded to fibre broadband last October and my desktop wired connection has proved to be rock solid with download speeds of just over 17 mbps. My laptop also has a reliable WiFi connection to the Plusnet provided router via its in-built 802.11n network adaptor. Signal quality is around 80.
However, download speeds to the laptop are incredibly erratic and occasionally fall to below 2 mbps. Any thoughts on why this might be happening and is it likely that the use of a more modern WiFi USB network adaptor would make a difference?
AlexB

[#2]

Do you live in an area with a lot of other wireless networks, such as a block of flats. Remember in the case of wireless you are sharing airtime with all the other networks in the area on the same and overlapping channels.
802.11`n` is still a respectable standard. So t start with I would try reconfiguring your router try channels 1,6 and 11 in turn to see if any give better performance.

[#3]

We live in a detached house. Despite this, changing the channel number to 1 has made a significant difference. Running OOKLA speed tests last night and this afternoon, I'm now experiencing download speeds between 13 and 16 mbps.
Thank you for the suggestion.
Alex