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I have two questions, that are related. My situation. I have two wifi networks available. Both are registered in wpa_supplicant.conf One has priority 10, another 20.

When I turn on wlan0 it picks 20 first if available, if not - picks 10. If it picks 20, and I then switch AP off, it automatically switches to 10.

Problem #1: When it initially connected to 20 it got new IP (via DHCP) (192.168..) When I switched network 20 and it reconnected to 10 I still have same IP. (192.168..) If connect to 10 first IP is like 10.0....

Problem #2: Is there a way to make it switch to higher priority AP when it still connected to previous one? Automatically.

UPD: More info on setup

OS: standard Debian. WiFi module: "Wi-Pi"

/etc/wpa_supplicant/wpa_supplicant.conf:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
        ssid="TereHomikust"
        psk="***"
        proto=RSN
        key_mgmt=WPA-PSK
        pairwise=CCMP
        auth_alg=OPEN
        priority=10
}

network={
        ssid="small device"
        psk="***"
        proto=RSN
        key_mgmt=WPA-PSK
        pairwise=CCMP
        auth_alg=OPEN
        priority=20
}

/etc/network/interfaces:

auto wlan0

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

small device network is AP running in Android phone. TereHomikust is my home network. I want ideally for my RPi always be connected to network with highest priority. Since both networks has different IP/mask setup and both provide DHCP service - I want to have appropriate IP when connected to each of those networks.

Currently, when RPi connected to small device with TereHomikust also available and I kill small device it reconnects to TereHomikust but keeps IP that it got from first networks' DHCP.

  • 1
    You have provided almost no information, so are unlikely to get helpful answers. Why do you want to switch (I suspect this is not the REAL question)? How have you set up? What OS? etc – Milliways Aug 7 '16 at 7:02
  • @Milliways I've put some details. Not sure what to put more. – Aleksandr Motsjonov Aug 7 '16 at 9:40
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If you are using Debian rather than Raspbian (which has different networking configuration) the /etc/network/interfaces should contain:-

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

What you have is not correct for any setup. manual allows external programs to configure IP and wpa-roam allows wpa_supplicant to react to network changes.

I don't know anything which will change from a working network to another, but this should trigger change if the current network becomes unavailable.

  • I use Raspvian (noob etc) Isn't Raspbian is Debian? I've seen iface wlan0 inet dhcp many many places, tutorials and it makes sense for me. As in - this interface should be configured with DHCP. Where is manual is when I want static configuration. (UPD, yeah, that' definitely not correct) What am I missing in my understanding? – Aleksandr Motsjonov Aug 7 '16 at 10:16
  • I guess the answer is that all those tutorials are old. and something has changed in ~2015sh? I found this. Quote > With the new network mods, DHCP is taken care of by a new package called dhcpcd. In order for this to work, the iface lines in /etc/network/interfaces need to be "manual" rather than "dhcp". – Aleksandr Motsjonov Aug 7 '16 at 10:24
  • Thank you. This did the trick. I will agree, that my second "Problem" is a bit strange and I guess I don't need it so much. I can restart machine when I need this. Thx. – Aleksandr Motsjonov Aug 7 '16 at 10:29
  • @AleksandrMotsjonov Raspbian is based on Debian but is customised for the Pi, and the current release uses a different networking system. See How do I set up networking/WiFi/Static IP for recommended configuration. What I have listed will work, but IMO dhcpcd works better (and manual applied even before). – Milliways Aug 7 '16 at 10:33

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