Really don't have enough information here.
Typically 5G WiFi has less interference, better performance, more reliable latency, and (if both devices support 802.11AC) some additional improvements. I'd definitely try the 5G. You might want to adjust the "roaming aggressiveness", or have your PC "forget" the 2.4GHz network as Windows sometimes has the tendency to switch wireless networks without reason if more then one are available.
Obviously ethernet would be best. I'm guessing you're living in the home of parents/family? So you will need to work out how cool everyone is with putting holes in walls and getting permission/assistance. It's definitely possible to do this a minimal skill set and still have a professional looking result. Please do your own research but the long and short is (if you have drywall and stud walls):
This is a gross generalization and there's a lot of options to make this better, but it's very doable. Lots of guides on youtube and the like to break down this kind of work.