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Using an ESP8266 I can get the RSSI of the Wifi network using Wifi.getNetworkInfo() or Wifi.RSSI(). But is there a way to know the actual connection speed in Mbps, after joining successfully a WiFi network?

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  • isn't it always 54?
    – dandavis
    Jan 12 '18 at 20:41
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    @dandavis Are your phone or laptop always connecting at 350 Mbps on 2.4 GHz or 867 Mbps on 5 GHz? of course not, it depends on the signal strength. That's the MAX connection speed with strong WiFi signals.
    – FarO
    Jan 13 '18 at 17:30
  • no, the ESP can't even talk on 5Ghz. My asus RT-AC68U claims ~54Mbps. Not sure what figure you're actually looking for, since you're never going to get more than a few dozen KB/s throughput.
    – dandavis
    Jan 13 '18 at 20:10
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    @dandavis I know that 5 GHz are not supported and that 54 Mbps are the maximum. Still, try to move the ESP far from the station, about the maximum distance that allows you to get a connection, and check in your router if the connection is still 54 Mbps. It shouldn't be, since in the datasheet it's stated that 22 Mbps have a better S/N and allow weaker signals. There will be a distance where 54 Mbps are not physically possible anymore and the connection will be established at 22 Mbps. My router doesn't show me the connection speed, please do this test :)
    – FarO
    Jan 13 '18 at 22:23
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Wifi modules decide on link speed based on signal strength. So you can estimate the link speed with signal strength, which you can get with WiFi.RSSI(network).

The datasheet of ESP8266 contains a table mapping RSSI to link speed under "Sensitivity":

  • -98 dBm: 1 Mbps
  • -93 dBm: 6 Mbps
  • -91 dBm: 11 Mbps
  • -75 dBm: 54Mbps
  • -71 dBm: 65Mbps, 72.2Mbps

Whenever these values are "minimum", "maximum" or "typical" remains unclear. These dBm limits are also quite low, which means the link speed will probably be capped by the other communication peer (your router). Here's the same table for a random D-link router, DI-624.

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