I just recently got a seller refurbished GS3 (that came in external flawless condition) that seems to do everything I want except give me the data speeds I pay for. I just upgraded from a GS2 and never had data speeds be this sporatic. I even called T-Mobile to notify them of the issue to make sure it wasn't something on their end. I average less than 350 KB/s (but will drop to 50KB/s or slower sometimes) according to many, many tests using the SpeedTest app by Ookla, though on rare occasions, I have gotten up to my 1.8 MB/s speeds (which is about what I should be seeing for my area) but it doesn't seem to hold for very long.
I'm rooted running CM11 (4.4.2) with baseband UVUEMJC and my IMEI is still visible. My APN seems to be on the appropriate one also. I'm not a complete noob to rooting and rom'ing my droids (or so I'd like to think), but I'm at a complete loss. Rom issue? Did I overlook something simple? I do apologize if I left out any information needed. I think my main concern is that since the phone is refurbished, I'm hoping it's not a hardware issue with the phone itself since I got it off of eBay (from a well trusted seller, but still). Is there anything I can do see the speeds I was saw when I had an S2? I do NOT have home internet, and I basically depend on tethering speeds for everything, so this is a big deal for me. Any help is appreciated.