I'm using TP Link a lot. (CPE510,220,710) and have fun of it because of frequency availability  so I decided to push even further and decided to upgrade WBS510 with sector antenna. But after installing I found a problem with negotiated rate despite of having good SNR. from short range, high platform. I'm formerly using CPE510 and got better performance compare to sector antenna. 

can you help me with this issue? any advice, firmware upgrade. (i'm not sure but i think I read some of R2d2 post about using different firmware from other product model).

thanks in advance. All