good night friends'm from Brazil, can give me strength, recently acquired a RBSXTG 5HPACD-L4, set up a link 5100metros with signal -58, but not spend more than 50Mbps, be the distance, or Setup

Try another channel.
What for protocol u use? 802.11, Nv2 ore what?
There are no distracting elements in the neighborhood?
Have you line of sight?