WiFi doesn't work unless Ethernet is also connected

Question

I have a problem with a brand new installation of Raspbian on a Pi 3 B+ (as well as on a Pi 4, with a stock install of Openhabian), one that has already come up several times. I have tried the solutions listed in those answers, modifying /etc/network/interfaces, but it didn't seem to help in the slightest - unless I have the Ethernet cable plugged in, the WiFi can't even get an IP, and with the cable connected, it's a crapshoot whether it gets a 169.254.x.x IP or a proper 10.0.x.x IP.

Contents of my interfaces config:

# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source /etc/network/interfaces.d/*
auto lo
iface lo inet loopback
auto eth0
allow-hotplug eth0
iface eth0 inet dhcp
auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

wpa_supplicant.conf has the correct data for connecting to the network in question:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
        ssid="SkyNet"
        psk="/snip/"
        key_mgmt=WPA-PSK
}

Additionally, it looks like while I can SSH into the device from the local network, the device can't communicate out towards the wider internet. The routing table doesn't show any obvious anomalies, though:

root@panel:/home/raspbian# ip route
default via 10.0.0.1 dev wlan0
default via 192.168.0.1 dev eth0 proto dhcp src 192.168.0.51 metric 202
default via 10.0.0.1 dev wlan0 proto dhcp src 10.0.10.10 metric 303
10.0.0.0/16 dev wlan0 proto dhcp scope link src 10.0.10.10 metric 303
192.168.0.0/24 dev eth0 proto dhcp scope link src 192.168.0.51 metric 202

Anyone have any ideas what I might be doing wrong?

Seeing as Raspberry Pi OS hasn't used Debian networking for 8 years, and you got the settings wrong for that. This shows little research. Network Manager is not used by default. — Milliways, Apr 24 '23 at 08:11
Your wpa_supplicant file doesn't include country=XX (with the correct country code) so rfkill is probably disallowing connections. — Dougie, Apr 24 '23 at 10:07
@Dougie Good catch! Weirdly enough, it was connecting on-and-off without it, but now it seems to be more consistent. The original issue persists, though, if I disconnect the cable, WiFi stops transmitting too... — Zalán Meggyesi, Apr 24 '23 at 10:48
Does this answer your question? How do I set up networking/WiFi/static IP address on Raspbian/Raspberry Pi OS? — Milliways, Apr 24 '23 at 22:46
Beautiful. I just noticed/confirmed that the Raspi Imager - the official utility for burning system images - does not add the country=XX key to the wpa_supplicant.conf even if you specify it before writing the image... — Zalán Meggyesi, Apr 25 '23 at 12:52
If you run a new image you should be prompted to specify location and if you configure with GUI it is set. — Milliways, Apr 25 '23 at 22:55
NOTE NetworkManager DOES NOT use wpa_supplicant. If you want to manually configure use nmcli. You are mixing incompatible networking services. — Milliways, Apr 25 '23 at 22:57

score 0 · Answer 1 · answered Apr 25 '23 at 09:30

0

Going off of @Milliways's comment, the solution in my case turned out to be commenting out everything in the interface config - /etc/network/interfaces - (aside from the inclusion rule) and restarting networking and NetworkManager.

answered Apr 25 '23 at 09:30

Zalán Meggyesi

99
1

WiFi doesn't work unless Ethernet is also connected

1 Answers1