TL;DR, usb-wifi works, but it's extremely (!) slow compared to onboard wifi, even though the dongle has a big antenna and a a better signal quality. I looked far and wide and did all I could find, but to no avail. Seems like this must be a settings issue...

PI 3B+ I'm running cat /etc/debian_version 9.9

  • I have tested the bandwidth with iperf3 on local network and with speedtest-cli and the same results came in.
  • The power management is OFF
  • sudo apt-get dist-upgrade has been done
  • firmware-realtek package is installed and up to date
  • The chipset is RTL8188CUS, which is supposedly supported by the firmware-realtek package


The onboard wifi has speeds around

pi@octopi:~ $ speedtest-cli Download: 29.29 Mbit/s Upload: 24.50 Mbit/s

with Link Quality

Link Quality=56/70 Signal level=-54 dBm

While the usb wifi has link quality

Link Quality=99/100 Signal level=67/100 Noise level=0/100

but speeds only

Download: 0.34 Mbit/s Upload: 2.46 Mbit/s

What is happening here?!

Any ideas warmply appreciated!

  • Are both connected to the same router? What is the timing if you ping the local router? – RalfFriedl Jun 17 '19 at 5:37
  • A small help : check the dbm TX power (use sudo ifconfig wlan1), check the MCS index (you must be connected to the AP) and the current bitrate of your connected device and his protocol used (802.11 ?) and the current Bandwidth (use sudo iw wlan1 info)... 802.11n allow 54Mb/s maximum , but he can allow most important bitrate depending of your device capabilities and conf. etc... Provide sudo iw wlan1 info (you must be connected to the AP) and sudo iw phy phy1 info outputs for more help (adjust the commands with your device name). Also , check sudo dmesg when device hot-plug. – Ephemeral Jun 17 '19 at 10:47

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