T-mobile Gateway

Antes you go down the rabbit hole making things more complicated you need to take some time and understand what you have NOW. 

Do you have the Nokia GW or the Arcadyan GW? (round can or square can with rounded corners)

How many bars does the simple LED display on it? (This is a very generic reporting by the way.) As stated 2 bars, yes this is weak. Maybe it can be improved with a little more effort.

Do you have a good feel for managing the T-Mobile gateway and know how to see the cellular metrics?

You can try different locations with the router/gateway to see if a stronger, cleaner signal can be received. Put the gateway on a long extension cord and take it for a walkabout. 

You can simply rotate the gateway a little at a time and see if the signal improves or not. In one of Nater Tater's YouTube videos he stated he had some improved results with the Arcadyan on its side. Sure I know it seems crazy but the reality is you want the 5G antennas to get the best signal wash over them so positioning of the gateway is important. I can and do improve my 5G signal with the Nokia GW just by rotating it so that the antennas on the front of the gateway face outside the window where it sits vs the other way around. It made a significant difference. The 5G signal will go from 3 bars to 4 bars. I won't go into the cellular metrics yet but the signal receive dBm values improve and the signal quality values also improves. Trying to not go too deep too fast as I don't know how much you might understand it if I dump a bunch on you too fast. 

Using the LED display alone only provides a very simplified view of how the cellular signals are received. Using the cellular metric values for the primary and secondary signals tells a much better story about how the gateway is working and the signal strength and quality of the signals. Positioning the gateway in the home with the LED info for a start is OK but to fine tune it and optimize the signals so it performs better demands using the cellular metrics especially if your home location is not in the best place for receiving good signals from the towers. 

Lxrod81, you state losing WIFI connection. Is it an actual loss of the wireless signal OR is it that the cellular signal from the tower is lost and then reconnecting? If your client reports no internet connection or connection lost it may be the cellular signal is down and not the WIFI. If the WIFI connection on a client is not stable be sure to check the drivers for the wireless NIC and make sure they are current. The more specific you are about the nature of the behavior the better.

There are a number of reasons for speeds falling and or disconnects. If T-Mobile engineers are working in the area where you live that will result in erratic behavior. Different times of the day and load on the cells serving the channels will impact speeds. If performance was good and now interrupted from time to time daily it is quite possible T-Mobile engineers are working on the equipment and their can be very frustrating. When they were working on the tower here speeds became unpredictable and there were repeated disconnects. In the beginning it was hard to tell if the clients were falling off the network or if the cellular signals were lost. 

My suggestion is to connect a client with a wired connection, if possible, so you can manage the gateway via the web interface with the 192.168.12.1 address. If you have the mobile application on your phone some information can be obtained using the  mobile application. 

Recording what the 4G LTE and 5G NR signals are is helpful. Recording the cellular metrics and posting information about the signals will help as you will be able to get better gateway positioning if you use that information. If the 5G changes from an n41 to n71 source you might be receiving signals from two sources and the gateway is not locking onto and holding a good signal. Your gateway might be out on the edge of the transmission so the signal is weak and it will be hard to improve or will take more work. Knowing where the tower is becomes important to have expectations. Close to a cell source usually provides reliable speeds. Being out on the edge of the cell signal often results in slow speeds and poor performance. Distance and obstacles are the enemy. 

Post more information and ask more questions. 

Suggestions to improve cellular reception:

• Contact support & determine if work/maintenance is being done on the tower. (external influence)
• Evaluate the location of the router with respect to the tower. 
• Make sure the router is located at the most optimal location in the home.
• Determine the location of the cellular tower & distance from the home
• Evaluate the terrain between the home & cell tower (clear view, trees, hills, buildings etc.. between home and tower)
• Relocate the router/gateway if possible to a better location in the home.
• Locate close to a window, with no metal screen

Post specific router information to the community conversation:

• Primary & Secondary internet connection information (RSRP, SNR, RSRQ values)
• Primary & Secondary cellular network information (PCI, Band, EARFCN/NR-ARFCN values)
• -Router Model & software version in operation (Nokia or Arcadyan)

With the PCI, physical cell identifier value it is possible to locate where the cellular signal originates. Using the web page cellmapper.net you can leverage the PCI information to find the tower where the cellular signal is broadcasting from. This helps to know how far the tower is from your home and also provides some clues as to how to go about improving the location fo the gateway in your home.

OK so going a bit deeper, here is a chart that helps understand the cellular metrics. When you do locate the gateway in a new location reading the metrics and using the chart helps you know how much better things are. If you improve the RSRP, RSRQ and SINR values better performance is the result.

The same here speeds were really fast, but now shitty and my devices keep losing Wi-Fi connection.