QRT 5 ac Configuration - Poor Throughput

RouterOS Beginner Basics
1

I have a 4km QRT 5 ac bridged link with a clear LOS and a clean frequency. I am using 5GHz A/N/ac, 20/40/80MHz Ceee, 802.11, Superchannel with CAT6 and all Gigabit Hardware and POEs. The source side is set up as bridge, and the destination is set as station bridge. My link shows it is connecting at 866Mbps, but when I test actual throughput, I am only getting 30Mbps of the original 90Mbps.

I have tried many variations of frequencies, band, and Channel Width with no better results.

What am I doing wrong?

2

With what have you measured the speed?
Measure with program Iperf. https://iperf.fr/iperf-download.php
This is much better than the supplied program