Anybody else having problems with connecting to 4g? When I switch from wifi to 4g, sometimes the 4g logo comes up, but it doesn't turn green. I get no connectivity until I either reboot or cycle it on airplane mode. Sometimes it takes a couple of cycles before I really get 4g connectivity. I actually returned my first phone for this problem, but the second phone is experiencing the same thing. Is it something I'm doing? Potentially something to do with tethering or using Samba filesharing?