Problem with RB1200 and RB433AH

We have problems with an antenna it has an input of 20 mb gives services approximately to 300 clients that connect with pppoe to RB1200 router and a RB433AH as bridge, between the RB1200 and RB433AH there a ptp with NanoStation m5, the RB433AH has 2 minipci of 400mw and 12dbi omni, a panel of 20 dbi and a dual polarity panel to one of the lan RB433 with rocket m5, the problem we are having is that they connect many more customers consumption does not exceed 5mb when a couple of weeks ago, consumption was between 12 and 15 mb, log in mikrotik see that when you are using more than 5 mb are beginning to see the logins rejections to RB1200
ej
: waiting for call …
: terminating …
: desconnected …

we wait for any suggestions that we can do
thank you very much in advance

Do you have any queues setup? How did you plan to limit the amount of traffic per user?

with pppoe profiles, it generate a dinamic queue, this works fine