Tmobile home internet SINR and RSRP issues

If the signal received is poor where it is you need to relocate the gateway. I suggest closer to a window and commonly a little higher up may help. Use the T-Mobile home internet application on your phone to do the location to determine the direction where the tower signal comes from. You can start there and see if the signal reception can be improved. It really is necessary to optimize the location of the gateway to get a better cellular connection. The cellular signals can reflect off surfaces so placement may require a little experimentation. Placing the gateway in the core of the home where appliances might interfere with the signal can be a significant problem. You can turn the gateway a bit clockwise or counter clockwise as you experiment. With some of the gateways just the exposure of the proper antennas toward the signal source can make a difference. I have the Nokia and I have to turn mine 180 degrees facing the front toward the outside to improve the reception. Even the components in the gateway can impact the signal reception to the antennas on some of the gateways. There is no rule of thumb. It always takes experimentation to find the best location. Every location is different and some homes have better signal exposure than others. If you can get the LED display to at least show three bars that is a good start. If it only reports two bars I would continue to experiment. Use the cellular metrics to fine tune it. Improving RSRQ and SINR will help it perform better. Sure stronger RSRP is good but improving signal quality and less signal noise helps as a cleaner signal does perform better. With the cellular modem just setting it in a convenient spot most often does not provide the best results. I had to really work at improving the reception to mine. 

Just in case you don’t have a table to translate the cellular metrics.

In my instance just a couple numbers improvement in RSRP resulted in a huge gain in speed and reliability. RSRP at -102 … moved the gateway 8 inches to the left and it measured -99 … doesn't sound like much but the gateway went from 3 bars "Good" to 4 bars "Very Good" … even though -99 still pretty much sucks … we went from spotty and sluggish 40 mbps to over 400 mbps … about a factor of ten. If this is anything like sound dB … a single digit is a factor of 10 so digits is a signal strength of about 100 as I understand it. 8 inch movement in same location made a hige difference.

It would be very surprising if the -3 dBm RSRP improvement is the only change responsible for the drastic speed increase. It might also be that the gateway locked onto a different cellular signal. Picking the factors apart to be certain of the results would really require looking at all the metrics and knowing if the frequency is now n41 and was n71 before or if the signal source is different. The signal source may have been impacted due to some shielding in the original location. It is great you were able to get improved reception. It really does pay to not just accept the initial results.