At this link they say this:
Get expanded Wi-Fi coverage and reliable speeds, plus 24/7 tech support.Someone should tell them that it is not 1999 anymore; sub 1MB/second service is not considered high speed by any reasonable person in the 21st century. I have tried. I have called support multiple times. Once they refunded me a full month's worth of service when they told me that they were aware of a problem and were working on it. I have heard tales of parts being on back order. I have heard about birds or squirrels nesting in towers and various other excuses.
I could be wrong but I don't believe that maintenance is the issue. That's because power cycling the gateway ALWAYS "fixes" the problem because the tower resets my usage and stops deprioritizing me.
The problem is that while this "fix" improves my speed temporarily it does that by deprioritizing another of their customers. I will get my 15 minutes of broadband speeds while someone else suffers. Then they hope I go away and slow me down again.
Why are my internet speeds too often closer to dial-up than broadband? Who knows? Maybe
My guess is that the problem is capacity - or bandwidth in geek speak. In suburban New York, where I am, T-Mobile does not appear to have sufficient bandwith to accomodate all of their customers. In fact their terms of service explicitly states that home internet customers are a lower priority to them than their mobile phone customers. In any case, if they did have sufficient capacity, then surely I would get the reliable broadband speeds that they advertise. Why else would they explicitly mention that home internet customers will get deprioritized if they actually had sufficient capacity? Some shark in a suit should investigate whether their advertisement of reliable, speedy broadband is reasonable in light of their capacity and subscriber numbers in densely populated suburban New York. Just sayin'.
In my experience the service is unreliable, if by service you mean 24/7 broadband. The good news is that Verizon home wireless internet has just set up shop in my neighborhood. Personally, I am deprioritizing T-Mobile!