Just received my HTC Vivid. Had an initial issue with data connection but was corrected by changing the APN manually. Now, I cannot turn on my portable WIFI hotspot. It keeps giving me the error message: "This is a temporary network problem that prevents the enablement of the Mobile Hoptspot function. Please retry later." ~ Is it because I am still under 4G and not 4GLTE?? Can someone help? Also tried dialing *#*#4636#*#* as directed but could not let me do any changes. Does AT&T have LTE restricted??