Mining Internetspeed

Hello Friends,

iam mining since 1 Week.

First i start with Gigabyte Rx 470 G1 with 4 GB.
I use ethminer and Dwarfpool. I have 20 Mh/s.

Yesterday i became a Sapphire R9 390 with 8 GB.
I have 34 Mh/s. That was slow......

I try the Dualminer. Wooooooooow
Between 50 - 56 Mh/s.
That ist good.

Now i put my Minerstation into my Office about 20 km away.
There i have W-Lan. But i couldnt mining with this connection. That is blocked.
With Handy i can mine......

But my question is how fast must be the internet for ethereum mining ?