Is it accurate though?
On fttc I'm 175m from my cabinet as the crow flies, 283m as reported by a GEA test and my router reports 11.6dB attenuation.
Your 2nd table indicates a line length of 500m for an 11dB attenuation with a downstream speed of 38Mbs.
You're not even on the ballpark with that figure!
Edited by IanBB (Sat 26-Aug-17 21:25:10)