May be it's just a not so powerful radio then. The device definitely supports the LTE bands used here in the USA by AT&T and Tmobile. Using LTE discovery app, my device has shown it's connected to LTE bands 2 4,5, 12 and 17. At one point or another.
If the device supports the correct bands, shouldn't the signal be fine?
What kind of optimizations are needed to have it perform like other Samsung devices that have support for the same band, but get good cellular signal on that band?
Can we flash the optimized radios from those other devices onto the A50?