tp-link: TL-WN725N

On the box it is called: TL-WN725N(US) v3

Official Site: https://www.tp-link.com/us/home-networking/usb-adapter/tl-wn725n/

This has been tested on Raspbian Buster (2019-07)

Purchase from https://www.lazada.com.my/products/tp-link-150mbps-wireless-n-nano-usb-adapter-wn725n-usb-20-i568056973-s1133310273.html

lsusb:

Bus 001 Device 003: ID 0bda:8179 Realtek Semiconductor Corp. RTL8188EUS 802.11n Wireless Network Adapter

Chipset: RTL8188EUS

Highlights:

  • Works on Rasbpian Buster out of the box

  • No additional drivers needed on Raspbian Buster (2019-07)

Issues:

  • Solved: Raspbian would switch interfaces names, even with "Predictable Network Names" enabled

  • Solved: dhcpcd did not recognize wlan1 as a wireless interface

  • Unsolved: Cannot get hostapd working

Notes:

  • wlan0 refers to the onboard wifi

  • wlan1 refers to the usb wifi

Hard Coding Network Names

Problem: With the WiFi plugged, on boot it could be randomly assigned either wlan0 or wlan1. This really makes it unpredictable. Even with "Predictable Network Names" enabled, the onboard wifi can be either wlan0 or wlan1, with the USB wifi being wlxXXXX.

Create /etc/udev/rules.d/70-my_network_interfaces.rules:

/etc/udev/rules.d/70-my_network_interfaces.rules
SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="dc:a6:32:aa:aa:aa", NAME="wlan0"
SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="50:3e:aa:aa:aa:aa", NAME="wlan1"

References:

dhcpcd Recognizing wlan1 as a wireless device

Problem: dhcpcd would not use wpa_supplicant on wlan1 because it was not recognized as a wireless device.

Modify /etc/dhcpcd.conf:

/etc/dhcpcd.conf
interface wlan1
env ifwireless=1

Try restarting dhcpcd:

sudo service dhcpcd restart

References:

Tips for Debugging

Below are some logs and files that helped me debug this.

Logs:

  • grep dhcp /var/log/syslog

  • grep wpa /var/log/syslog

Interesting files:

  • /etc/dhcpcd.conf

  • /lib/dhcpcd/dhcpcd-hooks/10-wpa_supplicant

Commands:

  • dpkg -L dhcpcd5

    • Displays which files were installed by dhcpcd