Galaxy S5 only connects to Edge not 4G anymore?

[sovietjet]

Hello all. I got a Galaxy S5 from USA T-mobile (Model number ... - 900T) and sent it as a gift to someone in Bulgaria. It was unlocked without problems so a local SIM card can be used instead. It worked fantastic, and the phone was connecting to the 4G there. Several weeks ago, the phone has only been connecting to Edge. 4G never connects anymore. What can be the reason for this? How can it be fixed?

 

[B. Diddy]

Welcome to Android Central! Your friend should contact the carrier and see if there are any known issues, like network problems or local towers in the process of being upgraded. A replacement SIM might be needed as well.