I just started using this phone, its data link is very slow. I do not think it is location related. I did not have the same problem with my previous LG phone ( I always saw 4G on my phone when I was in city).
There is only one place I can configure "Mobile Network"->Network mode GSM or not GSM on this phone. I have Data roaming enabled. The link symbol on the top of phone always shows "E" everywhere I go.