Z5 Dual keeps dropping mobile data signal

[anastvns]

Bought and received my Xperia Z5 Dual from a decently reputable seller on Amazon a few days ago. After putting in my SIM card, I had mobile signal (could call and text), but no data, so I took it into T-mobile, and they got that up and running. Ever since then, my data signal freqnently drops to zero bars, then comes back up within about a minute, then drops again a minute later. The wifi signal seems to be doing this too, although it appears to be at full bars all the time within my house, when I play a mobile game, I can tell it drops signal when it lags out every few seconds.

Should I return this one as broken and purchase a new one? I'm inclined to think the issue is not on my carrier's end, as I had no signal problems with this SIM card in my last phone, a very old Moto X. My friend suggested it was probably a hardware problem (specifically, faulty antenna board), but I don't know much about hardware, so I'm not sure whether to take her suggestion at face value or not. 

[MarlonUk1]

try to set your mobile network type to the strongest in your area. LTE only or WCDMA only.

settings>more>mobile networks>prefferd network type

[anastvns]

It was set to "LTE (preferred)/WCDMA/DSM". I changed it to LTE only, that gave me zero bars, no data or mobile service at all.

[Jake-SonyXperia · Accepted solution]

Hi anastvns,

Do you get the same results with WCDMA/GSM without LTE selected?

[Uliwooly]

@anastvns

Is your phone's LTE bands compatible with your network?

[anastvns]

I.. think this fixed my problem. Thank you! 

[anastvns]

@uliwooly

uhh, I have no idea.. 

[Jake-SonyXperia]

Sounds as though LTE is not available within your area or that the LTE bands are not compatible with your network carrier as advised by @uliwooly