sorry for bad english. I'm using Ubuntu 14.04 64 bit and I have a strange internet connection problem. When I'm at work I can access internet via DHCP wireless and wired without problems. When I'm at home with wireless connection or when I use tethering hotspot with my mobile phone I cant connect internet using DHCP. The only way to connect internet is to set manually the DNS ( in Network Manager. Why? With Ubuntu 12.04 I've never set DNS on DHCP and it worked fine... Thank you.

  • Is DNS ( the only thing that you need to change manually? i.e. you don't set static IP and subnet?
    – meccooll
    Jul 2 '14 at 21:30
  • Yes, only DNS!-
    – user299819
    Jul 16 '14 at 19:40

From the fact that your system connects at work via wired and wireless shows that your system works, and that the system at work is configured correctly. The failure of home wireless and "tethering hotspot" means that your home wireless router (and whatever you connect to with your phone) are not configured to share DNS information when you connect. You can fix this problem by accessing your home router configuration, and finding DHCP settings. You could use wireshark on Linux to monitor packets both as you connect at work, and fail to connect at home.

  • I dont think so: I have an other laptop at home, with ubuntu 12.04 and it works fine with not DNS configuration.
    – user299819
    Jul 2 '14 at 19:06
  • I assumed a single system, transported back-and-forth between "work" (where it can resolve DNS addresses) and "home" (where it cannot). Now, I suggest running zegrep 'wpa_supplicant|NetworkManager|lan' /var/log/syslog* at home (nonfunctional) and at work (functional). This will let you see messages logged by wpa_supplicant, NetworkManager or anything about "lan". Some of these messages may give useful information. Run the command on the "other laptop with ubuntu 12.04" to see what to expect on a working system.
    – waltinator
    Jul 15 '14 at 18:27

Connect to the troubled network and post output from nm-tool it should give you DNS server assigned by DHCP. See if that's correct, try to ping the DNS server(s)

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