In the last version of KDE Neon 5.10, i have a very annoying problem. I am connected to a ethernet connection and everithing works as expected, but every minute or so, a second wired conection appears and disconnects from the original one, just to not connect and go back to the original after a few seconds.
The second wired connection has a different mac address each time, and I don't know how to disable it.

This is a copy of my journalctl:


sep 05 14:20:23 CASANCHEZ-GNU dhclient[5385]: receive_packet failed on enp0s20f0u3i1: Network is down
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614023.4622] devices removed (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.1/net/enp0s20f0u3i1, iface: enp0s20f0u3i1)
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614023.4625] device (enp0s20f0u3i1): state change: ip-config -> unmanaged (reason 'removed') [70 10 36]
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614023.4975] dhcp4 (enp0s20f0u3i1): canceled DHCP transaction, DHCP client pid 5385
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614023.4975] dhcp4 (enp0s20f0u3i1): state changed unknown -> done
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <error> [1504614023.5213] platform-linux: do-change-link[35]: failure changing link: failure 19 (No such device)
sep 05 14:20:23 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614023.5218] device (enp0s20f0u3i1): failed to disable userspace IPv6LL address handling
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614031.8203] device (usb0): failed to find device 36 'usb0' with udev
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.8249] manager: (usb0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/35)
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9232] device (usb0): interface index 36 renamed iface from 'usb0' to 'enp0s20f0u3c2'
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9373] devices added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2)
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9374] device added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2): no ifupdown configuration found.
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9378] device (enp0s20f0u3c2): state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9384] device (enp0s20f0u3c2): link connected
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9402] keyfile: add connection in-memory (07a4acfa-8833-30e3-bac4-edd6c5eafa69,"Wired connection 2")
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9412] settings: (enp0s20f0u3c2): created default wired connection 'Wired connection 2'
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9437] device (enp0s20f0u3c2): state change: unavailable -> disconnected (reason 'none') [20 30 0]
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9573] policy: auto-activating connection 'Wired connection 2'
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9592] device (enp0s20f0u3c2): link disconnected
sep 05 14:20:31 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614031.9601] device (enp0s20f0u3c2): state change: disconnected -> unavailable (reason 'carrier-changed') [30 20 40]
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614032.3474] device (enp0s20f0u3c2): state change: unavailable -> unmanaged (reason 'removed') [20 10 36]
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <error> [1504614032.3632] platform-linux: do-change-link[36]: failure changing link: failure 19 (No such device)
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614032.3633] device (enp0s20f0u3c2): failed to disable userspace IPv6LL address handling
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614032.3639] devices removed (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2)
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614032.9778] device (usb0): failed to find device 37 'usb0' with udev
sep 05 14:20:32 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614032.9850] manager: (usb0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/36)
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0830] device (usb0): interface index 37 renamed iface from 'usb0' to 'enp0s20f0u3i1'
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0909] devices added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.1/net/enp0s20f0u3i1, iface: enp0s20f0u3i1)
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0909] device added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.1/net/enp0s20f0u3i1, iface: enp0s20f0u3i1): no ifupdown configuration found.
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0910] device (enp0s20f0u3i1): state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0925] device (enp0s20f0u3i1): link connected
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0938] keyfile: add connection in-memory (c40f101b-3bdf-357b-bc17-068ba94cca1d,"Wired connection 2")
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.0946] settings: (enp0s20f0u3i1): created default wired connection 'Wired connection 2'
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1100] device (enp0s20f0u3i1): state change: unavailable -> disconnected (reason 'none') [20 30 0]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1121] policy: auto-activating connection 'Wired connection 2'
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1125] device (enp0s20f0u3i1): link disconnected
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1127] device (enp0s20f0u3i1): state change: disconnected -> unavailable (reason 'carrier-changed') [30 20 40]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1424] device (enp0s20f0u3i1): link connected
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1426] device (enp0s20f0u3i1): state change: unavailable -> disconnected (reason 'carrier-changed') [20 30 40]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1434] policy: auto-activating connection 'Wired connection 2'
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1445] device (enp0s20f0u3i1): Activation: starting connection 'Wired connection 2' (c40f101b-3bdf-357b-bc17-068ba94cca1d)
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1446] device (enp0s20f0u3i1): state change: disconnected -> prepare (reason 'none') [30 40 0]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1450] device (enp0s20f0u3i1): state change: prepare -> config (reason 'none') [40 50 0]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1461] device (enp0s20f0u3i1): state change: config -> ip-config (reason 'none') [50 70 0]
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1464] dhcp4 (enp0s20f0u3i1): activation: beginning transaction (timeout in 45 seconds)
sep 05 14:20:33 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614033.1547] dhcp4 (enp0s20f0u3i1): dhclient started with pid 5520
sep 05 14:20:33 CASANCHEZ-GNU dhclient[5520]: DHCPDISCOVER on enp0s20f0u3i1 to 255.255.255.255 port 67 interval 3 (xid=0x90821b46)
sep 05 14:20:36 CASANCHEZ-GNU dhclient[5520]: DHCPDISCOVER on enp0s20f0u3i1 to 255.255.255.255 port 67 interval 7 (xid=0x90821b46)
sep 05 14:20:43 CASANCHEZ-GNU dhclient[5520]: DHCPDISCOVER on enp0s20f0u3i1 to 255.255.255.255 port 67 interval 12 (xid=0x90821b46)
sep 05 14:20:45 CASANCHEZ-GNU dhclient[5520]: receive_packet failed on enp0s20f0u3i1: Network is down
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614045.3130] device (enp0s20f0u3i1): state change: ip-config -> unmanaged (reason 'removed') [70 10 36]
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614045.3454] dhcp4 (enp0s20f0u3i1): canceled DHCP transaction, DHCP client pid 5520
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614045.3454] dhcp4 (enp0s20f0u3i1): state changed unknown -> done
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <error> [1504614045.3887] platform-linux: do-change-link[37]: failure changing link: failure 19 (No such device)
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614045.3887] device (enp0s20f0u3i1): failed to disable userspace IPv6LL address handling
sep 05 14:20:45 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614045.3889] devices removed (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.1/net/enp0s20f0u3i1, iface: enp0s20f0u3i1)
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614053.6545] device (usb0): failed to find device 38 'usb0' with udev
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.6621] manager: (usb0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/37)
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7357] device (usb0): interface index 38 renamed iface from 'usb0' to 'enp0s20f0u3c2'
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7434] devices added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2)
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7435] device added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2): no ifupdown configuration found.
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7437] device (enp0s20f0u3c2): state change: unmanaged -> unavailable (reason 'managed') [10 20 2]
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7453] device (enp0s20f0u3c2): link connected
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7479] keyfile: add connection in-memory (85fbd95d-1357-392e-ad34-66dc03ba6623,"Wired connection 2")
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7486] settings: (enp0s20f0u3c2): created default wired connection 'Wired connection 2'
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7654] device (enp0s20f0u3c2): state change: unavailable -> disconnected (reason 'none') [20 30 0]
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7662] device (enp0s20f0u3c2): link disconnected
sep 05 14:20:53 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614053.7678] device (enp0s20f0u3c2): state change: disconnected -> unavailable (reason 'carrier-changed') [30 20 40]
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614054.2150] device (enp0s20f0u3c2): state change: unavailable -> unmanaged (reason 'removed') [20 10 36]
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <error> [1504614054.2447] platform-linux: do-change-link[38]: failure changing link: failure 19 (No such device)
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614054.2449] device (enp0s20f0u3c2): failed to disable userspace IPv6LL address handling
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614054.2462] devices removed (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:2.0/net/enp0s20f0u3c2, iface: enp0s20f0u3c2)
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <warn> [1504614054.8467] device (usb0): failed to find device 39 'usb0' with udev
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614054.8525] manager: (usb0): new Ethernet device (/org/freedesktop/NetworkManager/Devices/38)
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614054.9671] device (usb0): interface index 39 renamed iface from 'usb0' to 'enp0s20f0u3i1'
sep 05 14:20:54 CASANCHEZ-GNU NetworkManager[1037]: <info> [1504614054.9758] devices added (path: /sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.1/net/enp0s20f0u3i1, iface: enp0s20f0u3i1)


Any help with the issue would be very appreciated

I have similar issue. Did you managed to resolve?