Unfortunately, your experience with the HL-3170CDW is extremely common. We had it happen and it is very well documented on Amazon. We found an Australian company that detailed the issue in their "fault of the week" page:

http://fixitfastelectronics.com/mfc9330cdw-9140cdn-emboss.ht...

The TLDR there is that the HL-3170CDW has a sharper-than-normal lift off angle from the fuser roller (the part that fails). Inexpensive toner is more sticky than the Brother-brand toner, so it causes undue fatigue on the part.

We had this same issue happen to us about 1000 pages after switching to an ultra-cheap, pour-in toner option. We first replaced the roller with a cheap one from Ebay that ended up causing the printer to overheat. Then we bought a custom manufactured roller from the aforementioned Australian company. That one has lasted us more than 3000 page so far, even with the cheap toner.

Note: if you elect to change the roller yourself, don't touch the heating element / bulb inside of the roller with your fingers!