switched 3 months ago - not so pleased

If the best you have seen with the T-Mobile cellular solution is 30 MBs download then that is really not that impressive. Please post more specific information about your gateway. Do you have the Nokia or the Arcadyan gateway? If you just picked up the T-Mobile solution 3 months ago it might be either. The Nokia is a cylindrical shape and the Arcadyan is squarish with rounded corners. It only matters for how to get the important information out of the gateway to have a better idea of the cellular signals you are able to receive. If all you get is 30 MBs down then that is more like a 4G signal vs having 5G. Your location may be a bit of a challenge for obtaining a good strong signal. You might need to consider adding an external antenna. If you cannot get a hard line & cellular or satellite are the only options I would still look closer at the T-Mobile solution. Even if you need to add an external antenna the cost in the long run could still be better. It is nice to not have a contract with a vendor that repeatedly bumps the price up every year. 

T-Mobile should be able to tell you where the tower is that your service is sourced from. If you have the cellular metrics information from the router with the PCI values it is possible to locate the tower using cellmapper.net by identifying the tower that has the PCI, physical cell identifier for the 4G & 5G signals. Each will have a PCI value that is associated with the cell delivering the signal.

Suggestions to improve cellular reception:

• Contact support & get more information on the tower location & cells.
• Evaluate the location of the router with respect to the tower. (internal influence)
• 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)