connecting two buildings and barbeque

I would like to ask for opinions and help on how to connect two buildings. The picture MAP in attachements will give you a better idea.

I have an internet access in the Building B. It is 25Mbps line served by WiFi router Speedport Entry 2. I need to get an internet access to the barbeque (BBQ) and Building A.

I have a direct line of sight:
from Building B to the Building A
from Building B to the south-east corner in front of Building A
from Building B to the barbeque.
I do not have a...

connecting two buildings and barbeque