home internet speeds

Which gateway do you have? The Arcadyan or the Sagemcon? 

Do you use the T-Mobile home internet mobile application to see the cellular metrics information?

If you post more information about the gateway and the cellular connections, i.e. the 4G LTE and 5G NR frequency/channel information it might help.

Do you use speedtest.net or fast.com to test the bandwidth?

Just at a glance based upon your description that is not looking good at all. It looks more like the gateway only has LTE and not the 5G secondary signal. Confirm the bands/channels i.e. frequency for both the 4G LTE and 5G NR signals. If you are only seeing the primary signal and not both then you need to touch base with T-Mobile support. They can see where the gateway connects, i.e. the tower and cell(s) and should be able to help out. If you reach a support engineer that can possibly make the signal lock on another more suitable tower and cells then that might be what it takes.

If you have the Arcadyan gateway and have been seeing this behavior pretty consistent power down the gateway and remove the SIM. Examine the SIM card carefully and then reinsert the SIM card. Some of the SIM card carriers have not been holding the SIM cards properly so the contacts might not be making proper connections. The SIM card saves and provides the user information for services so if your SIM card is not 100% maybe this has a bearing on the operation. This is an easy and quick action you can take before you take other steps to try to resolve the behavior.

I agree -101 is in the poor range. Your location must be on the edge of the n41 range which of course is not that far reaching. According to my research the mid band frequencies only have roughly a 3 mile radius for reach. Of course functional reach is less given you want respectable signal strength and minimal delay in flight. At least there is not a tremendous amount of noise on either band. Signal quality also is in the good range so that helps some. 

You might be able to improve the reception a little by rotating the gateway to influence the signal wash over specific antennas. It might help a little and provide a 2-3 dBm bump. While investigating external antennas I looked at the arrangement of the antennas in the gateway. The Nokia has them in an alternating radial pattern with the 5G - WIFI - 5G -WIFI … and a simple rotation a few degrees or 180 degrees can make a bit of difference. I have my gateway in a window with the backside facing in and I suppose what would be considered the front facing out toward the direction of the tower. By doing that I was able to go from 2 bars to 3 bars which in my case was a -3 dBm bump. Not stellar but every little bit of signal improvement helps. The RSRQ went up a bit too so that was also helpful. If you can improve the RSRQ, signal quality, this can improve performance as it results in less packet damage and fewer retransmissions via the TCP/IP stack operation. 

Of course the main objective is to get a bit more signal strength while maintaining a quality signal. There might be another n41 or n71 cell in the area that provides a stronger signal but if not then it comes down to improving what is available. I have also investigated the external antenna solutions at Waveform.com. They have the 4X4 and 2X@ MIMO antenna solutions and instructions for connecting to the gateway. Nice detailed documentation and their techs are knowledgeable and helpful. Sure it is an investment as the 4X4 MIMO antenna to take advantage of the n41 is ~$400 so not cheap. With the poor RSRP it would help collect the signal better but still it is hard to say how much it can do with that. They have a 30 day return policy and they are willing to work with you to help make it a success. I have seen some Reddit users post on their experience with the external antennas and when you have one the signal improvement and quality of the signal does make a big difference in performance. I considered it here but my signal is good and I get pretty impressive results with the same two bands. 

Try to find out the coordinates of the tower. With the PCI value for the 4G and 5G signals you should be able to find the cells via CellMapper.net and know what you are up against. I used CellMapper.net and found the 4G but the database here does not have the 5G yet. There are a limited number of cell towers here so I have a pretty good idea since options are very limited. Once you know where the antenna is fine tuning the gateway location is a bit easier. I used Google Earth to determine the distance, line of sight, to the various towers and evaluate the terrain. Cellular internet is a bit more of a challenge.

You might contact T-Mobile and see if they will provide the coordinates of that n41 cell. They KNOW the locations of their equipment. Some agents are clueless but there are some really good support agents I have dealt with so not all are at the same level. Sometimes it takes a bit of extra effort to get the answers but you just have to work the solution. It can be frustrating at times. I do get that.