Realtek 8111G ethernet does not work on 100 mbits, only 10

My Realtek 8111G has been working on 10 mbits for a while and I thought it was ok, I thought it was my internet provider plan. But recently I tried to connect real macbook to ethernet network (via adapter) and found out that my connection is 100 mbit and speedtest approved it. I have installed Realtek 8111G driver with MultiBeast, but it didn't help, the connection is still 10 mbit, while Asus B85M-G is capable of doing 1 Gbit.

How can I fix this? Any help, please.

EDIT
Moderator, could...

Realtek 8111G ethernet does not work on 100 mbits, only 10