Smb://x-gnome-default-workgroup/

Oct 3 10:33:33 canyon org.gtk.vfs.Daemon[1990]: ** (process:2455): WARNING **: Couldn't create directory monitor on smb://x-gnome-default-workgroup/. Error: Operation not supported by backend
Oct 3 11:56:30 canyon org.gtk.vfs.Daemon[1990]: ** (process:2455): WARNING **: Couldn't create directory monitor on smb://x-gnome-default-workgroup/. Error: Operation not supported by backend
Oct 3 12:22:03 canyon org.gtk.vfs.Daemon[1990]: ** (process:2455): WARNING **: Couldn't create directory monitor on smb://x-gnome-default-workgroup/. Error: Operation not supported by backend

I get those warnings in /var/log/syslog, my eth0 dies and I have to restart the network.
This is a UM16.04, all updates done, video is Nvidia GT640. Output of inxi -F follows:

System:    Host: canyon Kernel: 4.4.0-38-generic x86_64 (64 bit) Desktop: MATE 1.12.1  Distro: Ubuntu 16.04 xenial
Machine:   System: ASUS product: All Series
           Mobo: ASUSTeK model: H81M-K v: Rev X.0x Bios: American Megatrends v: 0703 date: 01/02/2014
CPU:       Quad core Intel Core i7-4790K (-HT-MCP-) cache: 8192 KB 
           clock speeds: max: 4400 MHz 1: 3999 MHz 2: 4021 MHz 3: 4037 MHz 4: 3999 MHz 5: 4015 MHz 6: 4017 MHz
           7: 4000 MHz 8: 3999 MHz
Graphics:  Card: NVIDIA GK107 [GeForce GT 640]
           Display Server: X.Org 1.18.3 drivers: nvidia (unloaded: fbdev,vesa,nouveau)
           Resolution: [email protected]
           GLX Renderer: GeForce GT 640/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 361.42
Audio:     Card-1 Intel 8 Series/C220 Series High Definition Audio Controller driver: snd_hda_intel
           Card-2 NVIDIA GK107 HDMI Audio Controller driver: snd_hda_intel
           Sound: Advanced Linux Sound Architecture v: k4.4.0-38-generic
Network:   Card: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller driver: r8169
           IF: eth0 state: up speed: 100 Mbps duplex: full mac: 10:c3:7b:69:68:d9
Drives:    HDD Total Size: 500.1GB (10.3% used) ID-1: /dev/sda model: WDC_WD5000BPKX size: 500.1GB
Partition: ID-1: / size: 451G used: 41G (10%) fs: ext4 dev: /dev/sda1
           ID-2: swap-1 size: 8.45GB used: 0.00GB (0%) fs: swap dev: /dev/sda5
RAID:      No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors:   System Temperatures: cpu: 71.0C mobo: 27.8C gpu: 45C
           Fan Speeds (in rpm): cpu: 0
Info:      Processes: 240 Uptime: 4 days Memory: 3224.5/15986.0MB Client: Shell (bash) inxi: 2.2.35