I just signed up to say, I have the exact same problem. Worked fine for about a month after I got the phone, then boom, dropped connections, skipping audio, etc. For weeks I hoped a software update would fix it but it hasn't. Some people are suggesting that this is a smartwatch issue. I do have four smartwatches, but I tried three factory resets and had the issue every time before pairing any watches (or installing anything else) so I'm inclined to say it's caused by something else. Also, it's not just a T-Mobile issue as I have AT&T. I was really hoping it wouldn't come to this, but I'm going to try to exchange it at the AT&T store later today. I'll post my results later.
Also, I have a problem where my Wi-Fi cuts out. At first I thought it was a problem with the internet, but then I realized that it happens at home and work and all other devices work fine. I'm not sure if anyone else is experiencing this or if it's related to the Bluetooth issue at all. It also still happened after factory resets for me. This is my first time buying a Samsung phone, and it may very well be my last. ??????
Update: AT&T is going to send me a replacement. I'll let you guys know how it goes. Seems that a replacement has been fixing the issue for most people.