TWO PCs connected via wifi for internet and local file sharing via LAN

[DonJuanMD]

Good day. I am trying to configure 2 PCs to do file sharing on LAN and connected to net via WIFI. I configured the two PCs to be connected via LAN by manually assigning IP but when I do file transfer it is utilizing WIFI not LAN. Any thoughts?

[Yeagdrasil]

I think the simplest way (assuming Windows) for myself would be set static routing on windows on seperate network.
E.g
Type into cmd

route print

Currently all connection that is aimed within my 192.168.0.0(My LAN) network will be sent via whatever interface that ends with 192.168.0.102 (my ethernet)

 

So to achieve what you want by seperating network access  on both computer,

set on cmd:

route ADD 192.168.x.0 MASK 255.255.255.0 x.x.x.x 

192.168.x.x being your network ip (usually one before router ip. assuming its a default home router setup)
If router ip is 192.168.1.1 then 192.168.1.0
if its 192.168.0.1 then 192.168.0.0
If it 192.168.100.1 then 192.168.100.0
x.x.x.x is the CURRENT PC's ETHERNET IP

 

THE MOST EASIEST METHOD if your router supports it (and wifi will be ONLY USED for internet connection isolated from LAN)
turn on WiFi Isolation  feature if your wifi router/access point supports it.

This will hide your other PC from Wifi network and force the windows to file share over LAN.

EDIT: expanding on Windows solution, another approach is maybe look into VLAN if you have Intel for ethernet and your router supports routing VLAN tagged packets.
All these might not sound casual-friendly so to speak but seperating two network interface for different access on Windows leans on power user than casual.
I truly hope you don't have to tinker with static route and settle with hardware solution
If you mess up and computer doesn't connect
 

route /f

will clear all relevant route and reboot to reset back to how it was before you started tinkering with it.