Okay, so I wasn't having any coverage with my ATT xs Max and I was having problems overall with ATT so I took my ATT phones back and signed up for T-Mobile. Now I'm having the same problems. Even though the LTE shows on the phone like there's coverage, it's not working. I'm new to T-Mobile so I don't know if it's just T-Mobile sucking or if it's this phone. But one weird thing is, I can't use Ookla Speedtest on my phone while it's on LTE. I can only use it on Wifi. When I use it on LTE it says "Test Failed to Complete. Check your internet connection and try again. I contacted Ookla via Facebook chat and they said I have to talk to T-Mobile about this, that it's their network that is the problem. The weird thing is, this same thing was happening on the ATT phone. I went to T-Mobile today and they said they don't know anything about this Ookla Speedtest thing (which I find very hard to believe). I uninstalled the Speedtest and reinstalled it and restarted my phone and still this happens. I'm not very tech savvy so I don't know what to do now. We have another xs max on our account and his is working fine but he's in a high coverage area and probably not noticing any problem at all anyway. Another problem, I can't use this phone as a modem. My iPhone 5s is using the Speedtest fine and I can use it as a modem. Not the XS Max.