I am trying to use my Ubuntu system as Wifi Hotspot, but for some reason Hotspot get disconnected on its own. Searching for the solution, I found this help : Why is my ethernet connection connecting and disconnecting repeatedly?

Reading through the above article I used the following command sudo killall dnsmasq as a result I manage to establish hotspot for around 5-10 sec before getting disconnected as against immediately....

Here's the system log (in case needed) tail -f /var/log/syslog :

Apr  1 23:31:42 NetworkManager[901]: <info> Starting dnsmasq...
Apr  1 23:31:42 NetworkManager[901]: <info> (wlan0): device state change: ip-config -> activated (reason 'none') [70 100 0]
Apr  1 23:31:42 dnsmasq[4159]: started, version 2.57 cachesize 150
Apr  1 23:31:42 dnsmasq[4159]: compile time options: IPv6 GNU-getopt DBus I18N DHCP TFTP IDN
Apr  1 23:31:42 dnsmasq-dhcp[4159]: DHCP, IP range 10.42.43.10 -- 10.42.43.100, lease time 1h
Apr  1 23:31:42 dnsmasq[4159]: reading /etc/resolv.conf
Apr  1 23:31:42 dnsmasq[4159]: using nameserver 220.226.6.104#53
Apr  1 23:31:42 dnsmasq[4159]: using nameserver 220.226.100.40#53
Apr  1 23:31:42 dnsmasq[4159]: cleared cache
Apr  1 23:31:42 NetworkManager[901]: <info> Activation (wlan0) successful, device activated.
Apr  1 23:31:42 NetworkManager[901]: <info> Activation (wlan0) Stage 5 of 5 (IP Configure Commit) complete.
Apr  1 23:31:42 NetworkManager[901]: <info> Activation (wlan0) Stage 4 of 5 (IP4 Configure Get) complete.
Apr  1 23:31:42 dbus[885]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
Apr  1 23:31:42 dbus[885]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'

Connection established at this point....now disconnecting after 10 sec...

    Apr  1 23:31:52 ntpdate[4194]: adjust time server 91.189.94.4 offset -0.011589 sec
    Apr  1 23:32:01 NetworkManager[901]: <info> (wlan0): IP6 addrconf timed out or failed.
    Apr  1 23:32:01 NetworkManager[901]: <info> Activation (wlan0) Stage 4 of 5 (IP6 Configure Timeout) scheduled...
    Apr  1 23:32:01 NetworkManager[901]: <info> Activation (wlan0) Stage 4 of 5 (IP6 Configure Timeout) started...
    Apr  1 23:32:01 NetworkManager[901]: <info> Activation (wlan0) Stage 5 of 5 (IP Configure Commit) started...
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol tcp --destination-port 53 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol udp --destination-port 53 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol tcp --destination-port 67 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol udp --destination-port 67 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --in-interface wlan0 --jump REJECT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --out-interface wlan0 --jump REJECT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --in-interface wlan0 --out-interface wlan0 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --source 10.42.43.0/255.255.255.0 --in-interface wlan0 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --destination 10.42.43.0/255.255.255.0 --out-interface wlan0 --match state --state ESTABLISHED,RELATED --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table nat --insert POSTROUTING --source 10.42.43.0/255.255.255.0 ! --destination 10.42.43.0/255.255.255.0 --jump MASQUERADE
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol tcp --destination-port 53 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol udp --destination-port 53 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol tcp --destination-port 67 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert INPUT --in-interface wlan0 --protocol udp --destination-port 67 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --in-interface wlan0 --jump REJECT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --out-interface wlan0 --jump REJECT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --in-interface wlan0 --out-interface wlan0 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --source 10.42.43.0/255.255.255.0 --in-interface wlan0 --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table filter --insert FORWARD --destination 10.42.43.0/255.255.255.0 --out-interface wlan0 --match state --state ESTABLISHED,RELATED --jump ACCEPT
    Apr  1 23:32:01 NetworkManager[901]: <info> Executing: /sbin/iptables --table nat --insert POSTROUTING --source 10.42.43.0/255.255.255.0 ! --destination 10.42.43.0/255.255.255.0 --jump MASQUERADE
    Apr  1 23:32:01 NetworkManager[901]: <info> Starting dnsmasq...
    Apr  1 23:32:01 NetworkManager[901]: <info> Activation (wlan0) Stage 5 of 5 (IP Configure Commit) complete.
    Apr  1 23:32:01 NetworkManager[901]: <info> Activation (wlan0) Stage 4 of 5 (IP6 Configure Timeout) complete.
    Apr  1 23:32:01 NetworkManager[901]: <warn> dnsmasq died with signal 9
    Apr  1 23:32:01 NetworkManager[901]: <info> (wlan0): device state change: activated -> failed (reason 'sharing-start-failed') [100 120 18]
    Apr  1 23:32:01 dnsmasq[4235]: started, version 2.57 cachesize 150
    Apr  1 23:32:01 dnsmasq[4235]: compile time options: IPv6 GNU-getopt DBus I18N DHCP TFTP IDN
    Apr  1 23:32:01 dnsmasq-dhcp[4235]: DHCP, IP range 10.42.43.10 -- 10.42.43.100, lease time 1h
    Apr  1 23:32:01 NetworkManager[901]: <warn> Activation (wlan0) failed for access point (Reppify Ubuntu)
    Apr  1 23:32:01 dnsmasq[4235]: reading /etc/resolv.conf
    Apr  1 23:32:01 dnsmasq[4235]: using nameserver 220.226.6.104#53
    Apr  1 23:32:01 dnsmasq[4235]: using nameserver 220.226.100.40#53
    Apr  1 23:32:01 dnsmasq[4235]: cleared cache
    Apr  1 23:32:01 NetworkManager[901]: <warn> Activation (wlan0) failed.
    Apr  1 23:32:01 NetworkManager[901]: <info> (wlan0): device state change: failed -> disconnected (reason 'none') [120 30 0]
    Apr  1 23:32:01 NetworkManager[901]: <info> (wlan0): deactivating device (reason 'none') [0]
    Apr  1 23:32:01 dbus[885]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper)
    Apr  1 23:32:01 dbus[885]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
    Apr  1 23:32:01 NetworkManager[901]: <error> [1333303321.565351] [nm-device-wifi.c:1815] nm_device_wifi_set_mode(): (wlan0): error setting mode 2