Hello Eric,
It is the 100Base-TX as with my setup I cannot use the 10Base-T.
As of now, after countless hours, I have tried the WR902AC at 2.4GHz with different dBm, with and without a WR802N as an access point, the WR902AC at 5GHz and in every single case I have had the same issue: the box suddenly hangs. The only constant along all these different settings has been the 3.3V PSU.
Perhaps my particular environment is too harsh for this kind of tweak and I should just forget about this whole endeavor…
All the best,
Bruno