Life, and Death of Pi

Runs a few hours, then loses the WiFi link. Why? Why does it need a reboot to get the wireless back? Why doesn't the router need to be reset?

From /var/log/syslog :

Jun 11 06:25:07 raspberrypi rsyslogd: [origin software="rsyslogd" swVersion="5.8.11" x-pid="1918" x-
info="http://www.rsyslog.com"] rsyslogd was HUPed
Jun 11 06:39:01 raspberrypi /USR/SBIN/CRON[3257]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] &&
[ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -ignore_readdir_r
ace -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete)

Jun 11 12:17:01 raspberrypi /USR/SBIN/CRON[3440]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Jun 11 12:39:01 raspberrypi /USR/SBIN/CRON[3450]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -ignore_readdir_race -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete)

++++++++++++++++ and then +++++++++++++

Jun 11 12:39:12 raspberrypi ifplugd(wlan0)[1603]: Link beat lost.
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: Executing '/etc/ifplugd/ifplugd.action wlan0 down'.
Jun 11 12:39:23 raspberrypi dhclient: Internet Systems Consortium DHCP Client 4.2.2
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: Internet Systems Consortium DHCP Client 4.2.2
Jun 11 12:39:23 raspberrypi dhclient: Copyright 2004-2011 Internet Systems Consortium.
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: Copyright 2004-2011 Internet Systems Consortium.
Jun 11 12:39:23 raspberrypi dhclient: All rights reserved.
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: All rights reserved.
Jun 11 12:39:23 raspberrypi dhclient: For info, please visit https://www.isc.org/software/dhcp/
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: For info, please visit https://www.isc.org/software/dhcp/
Jun 11 12:39:23 raspberrypi dhclient:
Jun 11 12:39:23 raspberrypi dhclient: Listening on LPF/wlan0/00:02:72:c3:99:74

Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: Listening on LPF/wlan0/00:02:72:c3:99:74
Jun 11 12:39:23 raspberrypi dhclient: Sending on   LPF/wlan0/00:02:72:c3:99:74
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: Sending on   LPF/wlan0/00:02:72:c3:99:74
Jun 11 12:39:23 raspberrypi dhclient: Sending on   Socket/fallback
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: Sending on   Socket/fallback
Jun 11 12:39:23 raspberrypi dhclient: DHCPRELEASE on wlan0 to 192.168.1.1 port 67
Jun 11 12:39:23 raspberrypi ifplugd(wlan0)[1603]: client: DHCPRELEASE on wlan0 to 192.168.1.1 port 67
Jun 11 12:39:24 raspberrypi ifplugd(wlan0)[1603]: Program executed successfully.
Jun 11 12:39:25 raspberrypi ntpd[2624]: Deleting interface #2 wlan0, 192.168.1.112#123, interface stats: received=419, sent=424, dropped=0, active_time=23922 secs
Jun 11 12:39:25 raspberrypi ntpd[2624]: 199.30.140.74 interface 192.168.1.112 -> (none)
Jun 11 12:39:25 raspberrypi ntpd[2624]: 195.216.64.208 interface 192.168.1.112 -> (none)
Jun 11 12:39:25 raspberrypi ntpd[2624]: 199.7.177.206 interface 192.168.1.112 -> (none)
Jun 11 12:39:25 raspberrypi ntpd[2624]: 198.199.97.84 interface 192.168.1.112 -> (none)
Jun 11 12:39:25 raspberrypi ntpd[2624]: peers refreshed
Jun 11 12:41:31 raspberrypi ddclient[2088]: WARNING:  cannot connect to 192.168.1.1:80 socket: IO::Socket::INET: connect: Network is unreachable

+++++++++++++ it keeps trying every 5 minues +++++++++ W Goin On?

Jun 11 14:06:32 raspberrypi ddclient[2088]: WARNING:  cannot connect to 192.168.1.1:80 socket: IO::Socket::INET: connect: Network is unreachable
Jun 11 13:17:25 raspberrypi kernel: imklog 5.8.11, log source = /proc/kmsg started.
Jun 11 13:17:25 raspberrypi rsyslogd: [origin software="rsyslogd" swVersion="5.8.11" x-pid="1956" x-info="http://www.rsyslog.com"] start
Jun 11 13:17:25 raspberrypi kernel: [    0.000000] Booting Linux on physical CPU 0
Jun 11 13:17:25 raspberrypi kernel: [    0.000000] Initializing cgroup subsys cpu
Jun 11 13:17:25 raspberrypi kernel: [    0.000000] Linux version 3.6.11+ (dc4@dc4-arm-01) (gcc version 4.7.2 20120731 (prerelease) (crosstool-NG linaro-1.13.1+bzr2458 - Linaro GCC 2012.08) ) #456 PREEMPT Mon May 20 17:42:15 BST 2013
Jun 11 13:17:25 raspberrypi kernel: [    0.000000] CPU: ARMv6-compatible processor [410fb767] revision 7 (ARMv7), cr=00c5387d