Maybe the wifi module/drivers are the problem. I have a old PC which randomly loses it's wifi when using the integrated wifi module, but it's working fine with external wifi dongle.
In Windows->Setings ->About ->Device specifications > System type property shows if the processor is x86 or x64 based. If its x64 based you should be able to install x64 OS.
I still have a Lumia 630m in some drawer now that I use when I travel to different countries alongside with my main phone(to be able to change SIM cards and because I like the maps app and the GPS is very accurate.