Wireless link 15 km

RB SXT G-5HPacD 15 km in 40 Mhz. Mikrotik themselves are the focus of satellite dishes 120cm.
Channel is very polluted, it will not hide. Seen all the same instability of the link, increasing the pings, sometimes even on the drawdown rate of less than 70 Mbps. Signal to Noise - 52 dB.
What else can I try, what are the options for settings? The frequency changes, try a width of 80 Mhz, the standard set “only AC”, no performance gain, stability worse. The reason for the radio or still damp glands in the software implementation of such a distance?
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