Hello how are you i have a ptp link rb912 with dish 30 the distance is about 250 meters its to close i have ccq 100/100 but when i do bandwith test i get only 30Mbps so can you tell me how can i get more than 30mbps i want a good data rate and mcs and what is the mcs i dont know what is it
The 30Mbps are probably capped by RB912 CPU. Bandwith test is CPU-intensive and not adapted to this device.
You should test bandwidth from client to client, not from the RB912 itself. For example, two computers running iperf with traffic passing thru the 912.
Its a ptp link and i did the bandwith test from the other device
RB912 should be able to give 100Mbps+ with a tcp test.
Try lowering the tx power on both ends.
A sxt or LHG may work better for the close distance
250 mtrs using 30dbi dish? too loud. 
try to reduce the power.