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I have a raspi 4B running headless v10 (buster). I do have a PC connected to a router and I have a raspi connected to a router via ethernet (eth0). With this setup everything runs, I can ssh into the raspi and the raspi can ping google.com. Now I was setting the raspi up as a host AP using dnsmasq.conf

interface=wlan0
dhcp-range=10.0.0.10,10.0.0.15,12h
#dhcp-option=option:router,10.0.0.1
#dhcp-option=option:netmask,255.255.255.0

Delays sending DHCPOFFER and proxydhcp replies for at least the specified number of seconds.


dhcp-mac=set:client_is_a_pi,B8:27:EB:::*
dhcp-reply-delay=tag:client_is_a_pi,2


address=/raspiwifisetup.com/10.0.0.1

and dhcpcd.conf:

interface wlan0
static ip_address=10.0.0.1/24

After joining the hotspot ssid opened by the raspi I can join a webserver via 10.0.0.1 and do some stuff. All of this works as expected.

BUT when I now try to ping google.com via the eth0 interface the call returns:
ping: google.com: Temporary failure in name resolution

I am still able to ssh into the raspi (via 192.168.178.88) since the eht0 interface is still up with the same IP but somehow I cannot reach the internet. ip route returns:

default via 192.168.178.1 dev eth0 proto dhcp src 192.168.178.88 metric 202
10.0.0.0/24 dev wlan0 proto dhcp scope link src 10.0.0.1 metric 303
192.168.178.0/24 dev eth0 proto dhcp scope link src 192.168.178.88 metric 202

When I now call sudo dhclient eth0 I am able to ping google.com again. After executing dhclient ip route returns.

default via 192.168.178.1 dev eth0
default via 192.168.178.1 dev eth0 proto dhcp src 192.168.178.88 metric 202
10.0.0.0/24 dev wlan0 proto dhcp scope link src 10.0.0.1 metric 303
192.168.178.0/24 dev eth0 proto dhcp scope link src 192.168.178.88 metric 202

Can anyone tell me why this is happening and is there another solution than calling "sudo dhclient eth0" everytime the raspi is in "host AP" mode?

EDIT: A little more background information on what I am trying to accomplish using this setup.

  1. At the start the rpi is in host mode having a hotspot AP open using dhcpcd.conf for address assigning.
  2. This hotspot's only purpose is for somebody to join the hotspot, go to a webserver and enter the credentials for an available wifi the rpi shall join afterwards. The credentials are copied into the wpa_supplicant.conf file.
  3. The rpi reboots after entering the credentials, deletes dhcpcd.conf and dnsmasq.conf and is in "client" mode and connected to the wifi. When the wifi is not available for a certain time, the rpi switches to host mode again and creates the conf files again.
  4. During all 3 states from above, the eth0 interface should be able to access the internet. Currently only when the raspi is in client mode and NOT in host mode, eth0 has internet access.

EDIT: Only "solution" so far: Calling sudo dhclient eth0 - which is not a good solution according to @Milliways

Slev1n
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1 Answers1

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The "tutorial" you linked is old and rather confusing.

It also omits a vital step in setting up an Access Point using dhcpcd

interface wlan0
    …
    nohook wpa_supplicant

This would have to be removed if trying to use for normal WiFi.

I can't guarantee that the process you used will actually work and it is far from clear what you end up with in dhcpcd.conf. There are a number of processes which claim to do this but are rather convoluted (it is just so much easier to add a wpa-supplicant.conf file for desired networks).

NOTE if you want an Access Point with no internet etc you should add nogateway See Prevent dhcpcd from configuring an interface in How do I set up networking/WiFi/static IP address on Raspbian/Raspberry Pi OS?

Milliways
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