I have had the same problem,havn't done much about it as yet.
But apparently Linux likes to have an Ethernet card rather than connection via USB,it keeps dropping the connection with usb.I searched for a fix,and found one,but it meant writing a script or something and it was out of my league.
Sorry dont know off hand where I found that fix,but it was on a Linux forum somewhere.
Dont know how techie you are,me not techie at all.
But an Ethernet card if you have one its the way to go...if you dont they are about a tenner and can be fitted easy enough,seek advice on Google.
Hope I have been of some help.