Hi all.
I need assistance with the following link/problem please.
Link=39Km.
Station=RB411, OS=V4.9. Radio=R52HN, Antenna=31dB grid.
AP=RB600, OS=4.9, Radio=R52HN, Antenna=31dB grid.

I've bought the R52HN's because of the specifications as per Mikrotik web site:"supporting up to 300Mbps physical data rates and up to 200Mbps of actual user throughput on both the uplink and downlink".

The signal strength on both ends are about -55 to -58 with "signal-to-noise" of about 57.
Radio settings in use: 5GHz a/n. HW retries=15, Ack=dynamic. Data rates=default. (I've tried many other settings). NStreme=on.
The problem is this;
From Station, I do bandwidth test (UDP). On receive I only get 35-40 Mb. On send, the link drops immediately, and stays down until I stop the sending.

So the cards do not perform anywhere near what the spec says, and the dropping of the link renders the whole process useless.
Any ideas please?

Edit
Dropped link fixed (apparently) by updating OS to V5 beta.
Sending is still VERY low (15Mb/s), Receiving goes only to 40Mb/s.

My requirements are low latency with at least 50Mb/s full duplex.

from your description i understand you use only one chain for this link .... that is up to 150Mbps for 40mhz chanel or 65 mbps for 20 mhz chanel..
for 300 mhz conection you need 2 antenas on station side and 2 antenas on ap side .... one with horizontal polarization and other on vertical polarization ....

i get up to 85 mbps full duplex on one chain on 6 km link with 40Mhz chanel and 2 411Ah ...

i get poor performance using rb 411 and rb 411 a