RB912UAG-2HPN POOR TX OUTPUT

HELLO,
I AM USING RB912UAG-2HPND MOSTLY 30 CLIENTS ON ONE SECTOR CURRENTLY ONLINE 14 USERS BUT THE VARIATION OF TX IS TOO LOW THAT EVEN IT CANT CROSS 2MB ALWAYS STUCK TO 130-500 KB ALL OVER CLIENTS TRIED DIFFRENT CHANNELS LATENCY IS TOO HIGH ALWAYS SIGNALS FROM CLEINTS ARE UNDER -69 TO ALL CURRENTLY I HAVE THREE BOX ALL HAVE SAME PROBLEM SLOW BROWSING LOW SPEED TO CLIENT END ETC… ANY CONGRATION CHANGES WHICH CAN BE MADE?