Signal issues with 5G gateway home internet

We have been using T-Mobile home internet for a while now using the original 4G LTE Gateway home internet device (small white box) which worked just fine. This week we were at a T-Mobile store and upgraded to the new 5G Gateway (silver cylinder) which we were told was amazing and much faster.  As soon as we hooked it up the signal strength was weak.  Internet service was slow at best and streaming anything online was impossible because the signal kept dropping.  I contacted customer service and spent over a hour on line trying to troubleshoot the device (moving it to different locations, resetting the device, etc.). The technician finally decided to send us a replacement device.  Instead of receiving a replacement 5G Gateway they sent me a refurbished Galaxy cell phone which is a whole other story, but it was back on the phone with customer service.  The second service technician said they would have engineering check our device which would take a few days to complete and they would contact me with the results. Three days later I received a call explaining my device was working perfectly but the cell tower we were receiving a signal from was overloaded and was scheduled to be upgraded by August 9th and until then our signal would not likely improve. The thing that makes no sense is the older device (4 LTE) worked fine receiving the signal from the same tower. The new device is supposed to work with either 4 LTE or 5G but is terrible. Has anyone else had a similar experience with the new 5G gateway device?