[Q] Difference between 4A.xxx and 4T.xxx basebands topic

Hello all, i have a question. I live in Italy, but my One m7 have the 4T.28.3218.04_10.33E.1718.01L baseband. AFAIK this baseband is for T-Mobile devices, but T-Mobile is not available in Italy. I know that WWE versions of basebands starts with 4A. So, there is a difference between these two vesrions? I'm asking for this because i have some issues with my device. Sometimes mobile data doesn't work, it seems that the phone sends requests but cannot receive any answer, so nothing works (internet, instant messaging, etc..) but phone calling works. If i turn off mobile data for some seconds, then i turn on again, all works but for a couple of minutes, then it hangs again. Could be this problem related to "wrong" baseband?
Thanks for your attention and sorry for my bad english, hope you can understand my problem.