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I have 2 RPi 3 Bs, each running Stretch and each with an EDIMax N150 USB device plugged in and no changes have been made to the default network configuration files.

When the PIs are turned on, I can use the WiFi icon in the status bar to connect each interface to a network. Once connected I can change the onboard WiFi to connect to a different network.

But if I change the USB WiFi to change to a different network, it disconnects and thereafter will not connect to any network. No visible errors are displayed. The only way to get the USB WiFi working again is to reboot.

Both PIs are acting the same way. It doesn't seem to make a difference if predictable names are enabled.

Any ideas why the USB WiFis are behaving this way?

Edit: This is a research setup. The onboard WiFi is used to connect to an isolated ad-hoc network, and the USB WiFi is used to connect to a router so that the performance of each node can be monitored, and also to provide Internet access so that software updates can be installed.

Edit II: I setup a wpa_supplicant-wlxMAC.conf file (where MAC is the MAC address for my USB WiFi), as suggested by @Milliways. This did not change the behaviour I describe above.

I suppose, if I wanted to change networks, I could manually edit the wpa_supplicant-wlxMAC.conf file for the new network and then reboot. I tried reconnecting the interface via the command line using dhcpcd -n wlxMAC, but that didn't do anything for the USB WiFi. When I check the status of dhcpcd (using systemctl status dhcpcd), I can see

dhcpcd[342]: control command: dhcpcd -n wlxMAC
dhcpcd[342]: wlxMAC: waiting for carrier

And then nothing

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  • If you want any sensible answer you need to explain how and why you have 2 WiFi interface. Raspbian manages only a single wpa_supplicant.conf file even though it lists both interfaces. If you want to manage them separately you need to do this manually.
    – Milliways
    Commented Jul 6, 2018 at 1:00
  • Thanks for your feedback @Milliways. I added some use case details to my description. Not exactly sure what you mean by "need to do this manually". I presume this means configuring via the command line, but I am not clear on the details.
    – Dave Isaacs
    Commented Jul 6, 2018 at 4:20
  • On the command line please execute the command sudo iw dev before and after disconnected wifi USB dongle and give us the results by editing your question.
    – Ingo
    Commented Jul 8, 2018 at 22:35

1 Answer 1

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See Use different wpa_supplicant files in How to set up networking/WiFi This lets you use a different wpa_supplicant.conf file for a specific wireless interface.

I am unsure whether the GUI link would manage these - I usually configure my files by hand.

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1
  • Tried this. Didn't seem to help. See my Edit II above.
    – Dave Isaacs
    Commented Jul 6, 2018 at 19:17

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