Good evening Ghernado,
the only difference between internet and LAN should be, that there are firewalls in between. At least, if you are using tcp/ip in your lan area. So if your firewall allow for the access, it will work. Now you only have the problem of having all those hackers and bot banging on another port in your systems 🙂 *scnr*
The only other option would be using netbios without tcp/ip, but the last pure "Windows" Lan, that I met, was shut of 4 Years ago.
Regards, Norgan