Unhappy [Q] Strange behavior on Data

I have (purchased 4mo ago) Tmobile Note3 phone on prepaid tmobile unlimited $70 (with 4G LTE) with Kitkat. Sometimes even with 4-5 bars with 4G sign it looses the data connection. Browsers wont load pages, email client just trying to sync. Google play's circle spinning and spinning. Everything works again after few second/minutes and stops again later. I did a factory reset and didnt help. Anybody know whats going on here?