I supposedly live in the T-Mobile 5G footprint, so I signed up for their Home Internet service as a trial. The modem/phone/box arrived within a few days and this morning I got around to trying it out.
For my testing. I used a wired connection to the T-Moble device. It took 3 tries with the password printed on the label, but it finally opened the admin page in Chrome. I disabled the WIFi on my MBP and on the T-Mobile device. I surfed to Google and searched for internet speed test sited. I went to the M-Labs site and ran the test several times. The fastest download was about 6.4 Mbps, and slowest 4.5 Mbps.
For the next test, I connected by iPhone 6s+ via usb to my mac and turned off wifi on the iPhone. I didn't want the iPhone to use the home cable internet to get to the internet. It indicated it was using LTE. The speed test showed 14.9 Mbps download.
The Spectrum cable internet in the house speed test returned 105 Mbps on a wired network connection.
For $50 per month, T-Mobile Home Internet is too slow. If it were $10 per month it might be useful as a backup for Spectrum, but my iPhone can provide that service at a higher level of performance.
I plan to return the device and cancel the service.