My PC doesn't show any other PC on LAN.

Hi there, this is probably a bit out of scope since this probably has more to do with firewall/network settings etc, but other than searching for solutions (and they do not need to be Dell specific etc.) on network posts/even the games' sites, I would recommend starting with the basics.

First try to see if your computer can ping other computers on the network using the command prompt using their IP addresses and ping command, and if it can, then try to have other computers ping yours (these computers all need to be local). If the computers can ping each way it still could be a firewall/network setting so then try temporarily disabling the firewall, the reason I would recommend trying the ping command first is to make sure that works at a minimum. From there the with firewall  disabled temporarily on both machines it should remove most issues, however if this does not allow the games to work correctly network settings/stacks would be the next place to look.

I hope this helps!

Brad 

Hi!You need to change some network settings.

Open "Network and sharing" center.

Then go for network changing adapter settings.

Press ALT key in order to see the menu settings.Choose advance settings from this menu.

Under"Adapters and binding"select the proper network adapter in the connection settings.

Move the green arrow to the top windows network adapter priority list.

Click "OK" to apply settings.