I have an Xperia 1 on T-mobile in the Northeast US. Since early April I have had issues with the phone not staying on LTE + network or "dropping back" to Edge. This usually occurs moving from one area of the city or town or something as simple as walking indoors or outdoors. I usually have to either reboot phone or use Airplane mode to turn wireless off and on again. I have reset wireless settings, checked APN with carrier and have already factory reset phone. I got a new SIM from T-mobile and used the same SIM in another phone without issues. Phone hasn’t ever been dropped or submerged and was working perfectly until about 2 months ago. I was thinking of upgrading to the MK 3 but if this is a Sony issue with firmware I’ll probably hold off or consider different phone options. Anyone else have this issue? If so, any solutions or assistance would be appreciated. I love the phone and would hate to have to go back to Samsung or Oneplus because of something dumb.