I ran a few frequency scans and let the snooper listen for a few minutes. After the tests, the 5GHz interface auto-selected settings of 5620/20-eeeC/ac/DP(21dBm). This channel and frequency looks clear to me (see screenshots), which I imagine is why the MT likes these settings, but I once again had poor 5GHz speeds, so I went ahead and rebooted. After reboot the MT again selected 5620/20-eeeC/ac/DP. The registration table for my laptop on 5GHz showed:
Signal strength: -55 | Tx rate: 173.3Mbps-20MHz/2S/SGI | Rx rate: 86.6Mbps-20MHz/1S/SGI
Another laptop showed similar weak numbers:
Signal strength: -34 | Tx rate: 72.2Mbps-20MHz/1S/SGI | Rx rate: 144.4Mbps-20MHz/2S/SGI
As you'd guess from the above, speedtest.net numbers were back in the 60 down/70 up range again (slower than my 2.4GHz numbers).
As discussed in an earlier post, I now went ahead and manually set the 5GHz interface to 20/40/80MHz eeCe/frequency 5700 and waited for radar detection to finish, then connected back to a 5GHz SSID. Registration numbers were strong again. Fluctuating a bit, but still ranging up to Tx: 866.6Mbps-80MHz/2S/SGI and Rx: 585Mbps-80MHz/2S/SGI. Speedtest numbers were back around 260Mbps down and 245Mbps up.
Why then would the 5620 setting yield such poor results? In building the channel table per @bpwl I likely would have chosen that one myself. Here's a sample of two frequency scans (first on the left, second on the right):
mikrotik-freq-scan-sshot-00.png
And here's a sample of the snooper output, sorted by channel:
mikrotik-snooper-sshot-00.png
I don't see any reason to pick 5700 over 5620, but clearly the end results are wildly different. Unless I'm misinterpreting the freq/snooper data, I get the impression I will have to pursue this empirically, trying all the apparently clear frequencies for performance, then building the channel table accordingly.
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