MORE SPECIFICATIONS ABOUT NETGEAR LG6100D

I'm not an expert with Netgear's mobile broadband products, so you are welcome to ignore me.  :smileyhappy:

I looked at the documentation for the LG6100D and it looks like it's specifically designed to be used with Sprint's cellular network, so you probably cannot use its built-in LTE modem.  It also does not appear to accept a USB modem, so your Internet key will not work.

From what I can tell, Netgear has 4 classes of mobile broadband products:

1. USB Modem
   
   These are probably the same as your Internet key.  I think they are not available in Italy.
   
   
2. Mobile Hotspot
   
   These are cellular modems with Wi-Fi.  Netgear calls them Aircards.  There is an optional cradle (like the DC112A) that can accept an Aircard and provide expanded capabilities (extra antennas, Ethernet and USB ports).
   
   
3. LTE gateway
   
   These are cellular modems with Wi-Fi, Ethernet and USB ports.  The LG6100D is a LTE gateway designed for Sprint.  I found the Netgear MBR1517, which appears to be designed for the European market, so it may work with one of your sim cards.
   
   
4. USB modem compatible router
   
   This is a Wi-Fi router that can accept a USB modem.  It looks like it's available in Italy as the MBRN3000.  Your Internet key may work with this, but you should confirm that it is supported before you purchase.  Unfortunately, I'm pretty sure that this will not amplify your cellular signal.