THank you Sriram,
I tried all your points. I completely disabled Firewall but the problem is still there.
when I'm connected to Vpn I am able to ping the host.
HAve also tried to launch Sap logon using the command line...but unfortunately no good news.
WHat is getting me crazy is that this thing is happening from 2 different PC in my office (both Windows 10), while my MacBook that uses SapGui for Java works fine! But is not possible that is something related with a compatibility issue because until few days ago everything worked fine also on Windows 10...