For some reason I have yet to understand, when I upgraded from 11.10 (working flawlessly) to 12.04, internet seems not to work after a while and the only solutions are either to reboot or to disable and enable wireless.
This is my network device, 02:00.0 Network controller: Intel Corporation Centrino Wireless-N + WiMAX 6150 (rev 67)
I could attach some of my latest logs but I don't know how to format that properly. This looks problematic (I changed the mac and SRC just in case):
lobato kernel: [ 9561.859976] wlan0: no IPv6 routers present lobato kernel: [ 9563.341424] [UFW BLOCK] IN=wlan0 OUT= MAC=01:xx:xx:xx:xx:01:f4:ec:38:be:d6:3c:08:00 SRC=22.214.171.124 DST=126.96.36.199 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2 lobato kernel: [ 9564.764594] [UFW BLOCK] IN=wlan0 OUT= MAC=40:xx:xx:xx:xx:58:ec:55:f9:41:08:f7:08:00 SRC=188.8.131.52 DST=184.108.40.206 LEN=32 TOS=0x00 PREC=0x00 TTL=1 ID=13535 PROTO=2 lobato NetworkManager: <info> (wlan0): IP6 addrconf timed out or failed.