@vivek first, find out what your PCs existing WiFi IP address and subnet mask is. I’d guess that the subnet mask is 255.255.0,0, so any address matching the first two numbers is going to Wifi. If so, you’ll need to set the IP address for the PC Ethernet port so that the address falls outside the wifi subnet mask. If your router is using 192.168.x.x, you could use 10.x.x.x or 172.16.x.x (see here for private IP address ranges https://www.ibm.com/docs/en/networkmanager/4.2.0?topic=translation-private-address-ranges ).
Once you have worked that out, set the Duet to an address in that range.
Alternatively, you can also test your current setup by disconnecting from WiFi. Then all traffic should go via the Ethernet port.
Please post your config.g so we can see how you have it set up currently. You can also send ‘netstat -a’ in a Windows command line to get the current Windows settings.
Ian