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I have a Raspberry Pi device which runs on Raspbain Linux. The device performs well on wlan0 but from the last few days, it became offline (disconnected from the network). I thought of looking into some logs and found daemon.log file in /var/log/ which contains some useful information about the network connectivity wlan0. I did cat daemon.log | grep wlan0 and it showed all the logs.

I tried to understand all the logs and got the basic idea but just wanted to know a bit more about the logs as few terms are not understandable.

Apr  9 04:59:33 device dhcpcd[332]: wlan0: carrier acquired
Apr  9 04:59:33 device dhcpcd[332]: wlan0: adding address fe80::bac5:f37d:9bb4:65df
Apr  9 04:59:33 device dhcpcd[332]: wlan0: IAID eb:d3:4c:54
Apr  9 04:59:34 device dhcpcd[332]: wlan0: soliciting a DHCP lease
Apr  9 04:59:34 device dhcpcd[332]: wlan0: offered 192.168.0.57 from 192.168.0.1
Apr  9 04:59:34 device dhcpcd[332]: wlan0: soliciting an IPv6 router
Apr  9 04:59:34 device dhcpcd[332]: wlan0: probing address 192.168.0.57/24
Apr  9 04:59:35 device avahi-daemon[325]: Joining mDNS multicast group on interface wlan0.IPv6 with address fe80::bac5:f37d:9bb4:65df.
Apr  9 04:59:35 device avahi-daemon[325]: New relevant interface wlan0.IPv6 for mDNS.
Apr  9 04:59:35 device avahi-daemon[325]: Registering new address record for fe80::bac5:f37d:9bb4:65df on wlan0.       *.
Apr  9 04:59:38 device dhcpcd[332]: wlan0: leased 192.168.0.57 for 86400 seconds
Apr  9 04:59:38 device avahi-daemon[325]: Joining mDNS multicast group on interface wlan0.IPv4 with address 192.168.0.57.
Apr  9 04:59:38 device avahi-daemon[325]: New relevant interface wlan0.IPv4 for mDNS.
Apr  9 04:59:39 device avahi-daemon[325]: Registering new address record for 192.168.0.57 on wlan0.IPv4.
Apr  9 04:59:39 device dhcpcd[332]: wlan0: adding route to 192.168.0.0/24
Apr  9 04:59:39 device dhcpcd[332]: wlan0: adding default route via 192.168.0.1
Apr  9 04:59:39 device dhcpcd[332]: wlan0: removing route to 192.168.0.0/24
Apr  9 04:59:47 device dhcpcd[332]: wlan0: no IPv6 Routers available
Apr  9 05:15:49 device dhcpcd[332]: wlan0: carrier lost
Apr  9 05:15:49 device dhcpcd[332]: wlan0: deleting address fe80::bac5:f37d:9bb4:65df
Apr  9 05:15:49 device avahi-daemon[325]: Withdrawing address record for fe80::bac5:f37d:9bb4:65df on wlan0.
Apr  9 05:15:49 device avahi-daemon[325]: Leaving mDNS multicast group on interface wlan0.IPv6 with address fe80::bac5:f37d:9bb4:65df.
Apr  9 05:15:49 device avahi-daemon[325]: Interface wlan0.IPv6 no longer relevant for mDNS.
Apr  9 05:15:49 device dhcpcd[332]: wlan0: deleting default route via 192.168.0.1
Apr  9 05:15:49 device avahi-daemon[325]: Withdrawing address record for 192.168.0.57 on wlan0.
Apr  9 05:15:49 device avahi-daemon[325]: Leaving mDNS multicast group on interface wlan0.IPv4 with address 192.168.0.57.
Apr  9 05:15:49 device avahi-daemon[325]: Interface wlan0.IPv4 no longer relevant for mDNS.

So above, it says carrier accquired and 192.168.0.57 was offered by the router(192.168.0.1). It tried to connect on that IP and leased was given for 86400 seconds (24hrs). But after this, when it says wlan0: adding route to 192.168.0.0/24. What does it means.?

I am not able to understand whats actully happening with it. Can anyone please explain this to me.?

Thanks

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Very quick overview:

dhcpd handles Dynamic Host Configuration Protcotol (DHCP) responses, in other words, IP addresses that are assigned to your computer by your home router. This assignment ("lease") comes with a duration ("24 hrs").

avahi-daemon handles Zeroconf/Bonjour messages, in other words information about local devices in your homenetwork, especially for Apple devices (or other devices that use this protocol).

The adding route message together with the network range means that after you got an IP address via DHCP, your networking setup was made aware that all these addresses (somewhat simplified 192.168.0.0-192.168.0.255, in your example) are now reachable via wlan0. This is typically done by executing ip route add ... or a similar command. Try ip route show as root to see your current routes.

You can easily find more information, and introduction into networking, with a bit of googling.

None of this will help in debugging the connection problem. Have a look at the output of dmesg or at /var/log/syslog* instead.

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