Exact same issue here, recently done dist-upgrade from 14.04 LTS to 16.04, I did not have this problem at all before. Not running on VM.
Linux server 4.4.0-75-generic #96-Ubuntu SMP Thu Apr 20 09:56:33 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux Using Wired ethernet, happens 2-3 times at least a week and need to reboot. others have other NIC than Realtek ? RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller driver=r8169 driverversion=2.3LK-NAPI firmware=rtl8168e-3_0.0.4 03/27/12 syslog not showing any hints to what happened other than already mentioned above. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to network-manager in Ubuntu. https://bugs.launchpad.net/bugs/1586528 Title: Avahi-daemon withdraws address record Status in avahi package in Ubuntu: Invalid Status in network-manager package in Ubuntu: Confirmed Bug description: For some reason, if I leave my Ubuntu VM up for a prolonged period of time the machine will lose connection to the network. ip addr shows that the nic port no longer has an address and an examination of the syslog shows this: May 27 14:19:38 matt-VirtualBox avahi-daemon[590]: Withdrawing address record for 10.0.2.15 on enp0s3. May 27 14:19:38 matt-VirtualBox avahi-daemon[590]: Leaving mDNS multicast group on interface enp0s3.IPv4 with address 10.0.2.15. May 27 14:19:38 matt-VirtualBox avahi-daemon[590]: Interface enp0s3.IPv4 no longer relevant for mDNS. for no known reason. The only reliable way to get the network to come back (that I have found) is a full reboot. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: avahi-daemon 0.6.32~rc+dfsg-1ubuntu2 ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8 Uname: Linux 4.4.0-22-generic x86_64 ApportVersion: 2.20.1-0ubuntu2 Architecture: amd64 CurrentDesktop: Unity Date: Fri May 27 15:11:34 2016 InstallationDate: Installed on 2015-10-22 (218 days ago) InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021) SourcePackage: avahi UpgradeStatus: Upgraded to xenial on 2016-03-30 (58 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1586528/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp