How can I route LAN only to guest (LAN accessed only guest)

[The Torment]

So I have a software that only runs in LAN without internet access. If I connected to internet using WLAN (so I can operate it from another computer using teamviewer for instance) that software won't work.

I had an idea which is isolate LAN from WLAN and let it run in guest machine without being interacted with WLAN. GOT IT?!

Any ideas to run the software with internet access or run it from another computer?

[noteirak]

I fail to see how is this related to Virtualbox? The fact you run a VM is most likely irrelevant, especially if it is influenced by networking.