Hi.
Just looking briefly at this; at the top of my head ~-61 dB RSSI, your probably only good for ~400/400Mbit using 40MHz in perfect conditions( yes it might say something > 400MHz ), but once you add data I guarantee that's the beginning of your Eb/N0(
https://en.wikipedia.org/wiki/Eb/N0) journey .( aka bit error rate)
You don't appear to show the Signal to Noise ratio which is the next biggest factor after signal strength, for each modulation mode( BPSK/QPSK/QAM/CODING-(e.g 3/4,5/8) , there will need to be a MINIMUM SNR to decode the specific at-point-in-time modulation mode.
For example ( rough figures, but plenty of literature on wifi SNR on google, or you can do the math ).
1. BPSK (Binary Phase Shift Keying)
Minimum SNR: ~ 6-8 dB
Used in: Very basic Wi-Fi standards like 802.11b at low data rates.
2. QPSK (Quadrature Phase Shift Keying)
Minimum SNR: ~ 8-12 dB
Used in: 802.11b/g at medium data rates, especially in noisy environments.
3. 16-QAM (16-Quadrature Amplitude Modulation)
Minimum SNR: ~ 15-20 dB
Used in: 802.11g/n/ac at medium-high data rates.
4. 64-QAM (64-Quadrature Amplitude Modulation) (say ~120-Mbit @ 40MHz, per chain )
Minimum SNR: ~ 20-25 dB
Used in: 802.11n/ac/ax at higher data rates, commonly used in modern Wi-Fi standards.
5. 256-QAM (256-Quadrature Amplitude Modulation) (say ~180-Mbit @ 40MHz, per chain )
Minimum SNR: ~ 25-30 dB
Used in: 802.11ac/ax for even higher data rates, found in very high-speed Wi-Fi (e.g., Wi-Fi 5/6).
6. 1024-QAM (1024-Quadrature Amplitude Modulation) (~333 Mbit @ 40MHz, per chain )
Minimum SNR: ~ 30-35 dB
Used in: 802.11ax (Wi-Fi 6), very high-speed environments with clear channels.
Now take your -61dBm signal and subtract say 25dB (Item 4 above, for lets say 120Mbit worth of single chain(vertical or horizontal RF!!)= -86dBM(yes the backwards math applies) will be the minimum gap to the noise floor below. So if you get your mikrotik's to check the noise floor, you had better hope its -86dBm or quieter eg > -100dBm.
Now then there is interference, which can be from radar, other RF users in your channel/spectrum, so if you get spikes that take that -86 to say -80, them bam, lost packets..., yes the radio's can dial down modulation, but its not a perfect science, and yes there is built in coding rates to help recover in flight errors, but all in all its a problem.
Anyhow, I' start at the start, and move to 20MHz channel width which will improve your dBHz density, and see if you can lower your modulation modes and start from there. I'd also start looking at using alternate frequencies in your testing( to see if its an external noise source )
MIKROTIK SIGNAL TO NOISE.png
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