I have some questions about the bandwidth test inside routeros.

The tcp test between one SXT 5 Lite and one rb912 is showing 40 mbit. (The testserver is running on a different router inside our datacenter.)

But a speed test to the internet from the SXT is showing 10 mbit. The same speedtest on wired network in our datacenter is showing more than 40.

I have this problem now twice that theoretically i have good signal and speed, but downloads are slow.

Why? How to troubleshoot?

very normal........

is this how nv2 is working regarding tcp window size and latency?

I don't think NV2 has anything to do with window size, and only little with latency.
My NV2 link performs great, also with TCP test (done using iperf).

@onnoossendrijver:

The window size is calculated for the latency of the link and nv2 add latency to the link.

How many connections are you using in iperf?

@onnoossendrijver:
The window size is calculated for the latency of the link and nv2 add latency to the link.
How many connections are you using in iperf?

You are right about the window size and how that's related to the latency.
With only 1 TCP session in iperf I get speeds of 180 to 210 mbit/s (2 spatial stream 300mbit/s link).

Next client and again the same. 97 / 97 mbit with btest and 30 / 30 with speedtest.net. Wan connection and the whole network is idling almost.