Monitors-periodically-turn-off on Ubuntu 18.04

[schadsey]

I recently upgraded from Xubuntu 17.10 to 18.04 and have started seeing something similar. My system is a Dell Latitude 5580 that is connected to a Dell D6000 docking station via USB-C. I posted the following in https://bugs.launchpad.net/ubuntu/bi...x/+bug/1763594 but I don't know for sure if that bug is what is going on here.

I've been getting similar disconnects on a Dell Latitude 5580 that is connected to a Dell D6000 docking station via USB-C. I'm also using DisplayLink driver version 4.4.24 (https://www.displaylink.com/downloads/ubuntu) in order to connect to two external displays. With Ubuntu 17.10 I was not seeing any disconnects. With 18.04 I see at least one per day where the external monitors go dark, and these messages in syslog:

Nov 13 10:26:39 steveclx5580 kernel: usb 3-1: USB disconnect, device number 2
Nov 13 10:26:39 steveclx5580 kernel: usb 3-1.2: USB disconnect, device number 3
Nov 13 10:26:39 steveclx5580 kernel: usb 3-1.2.2: USB disconnect, device number 5
Nov 13 10:26:39 steveclx5580 kernel: xhci_hcd 0000:3d:00.0: xHCI host controller not responding, assume dead
Nov 13 10:26:39 steveclx5580 kernel: xhci_hcd 0000:3d:00.0: HC died; cleaning up
Nov 13 10:26:39 steveclx5580 kernel: usb 4-1: USB disconnect, device number 2
Nov 13 10:26:39 steveclx5580 kernel: usb 4-1.1: USB disconnect, device number 3
Nov 13 10:26:39 steveclx5580 kernel: cdc_ncm 4-1.1:1.5 enx9cebe8551508: unregister 'cdc_ncm' usb-0000:3d:00.0-1.1, CDC NCM
Nov 13 10:26:39 steveclx5580 NetworkManager[1089]: <info> [1542122799.4322] device (enx9cebe8551508): state change: unavailable ->
unmanaged (reason 'removed', sys-iface-state: 'removed')

This morning I tried the linux-oem package based on comments in this bug report.
$ uname -a
Linux steveclx5580 4.15.0-1024-oem #29-Ubuntu SMP Tue Oct 16 08:14:23 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

I am still seeing disconnects, and they are more frequent than before:

Nov 14 10:43:46 steveclx5580 kernel: usb 3-1: USB disconnect, device number 2
Nov 14 10:43:46 steveclx5580 kernel: usb 3-1.2: USB disconnect, device number 3
Nov 14 10:43:46 steveclx5580 kernel: usb 3-1.2.2: USB disconnect, device number 5
Nov 14 10:43:46 steveclx5580 kernel: xhci_hcd 0000:3d:00.0: xHCI host controller not responding, assume dead
Nov 14 10:43:46 steveclx5580 kernel: xhci_hcd 0000:3d:00.0: HC died; cleaning up
Nov 14 10:43:46 steveclx5580 kernel: usb 4-1: USB disconnect, device number 2
Nov 14 10:43:46 steveclx5580 kernel: usb 4-1.1: USB disconnect, device number 3
Nov 14 10:43:46 steveclx5580 kernel: cdc_ncm 4-1.1:1.5 enx9cebe8551508: unregister 'cdc_ncm' usb-0000:3d:00.0-1.1, CDC NCM
Nov 14 10:43:46 steveclx5580 upowerd[2272]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:1c.4/0000:05:00.0/0000:06:
02.0/0000:3d:00.0/usb4/4-1/4-1.1/4-1.1:1.1
Nov 14 10:43:46 steveclx5580 upowerd[2272]: unhandled action 'unbind' on /sys/devices/pci0000:00/0000:00:1c.4/0000:05:00.0/0000:06:
02.0/0000:3d:00.0/usb4/4-1/4-1.1/4-1.1:1.0
Nov 14 10:43:46 steveclx5580 dhclient[3858]: receive_packet failed on enx9cebe8551508: Network is down

I do regularly suspend/resume this laptop, but the latest disconnects have happened without a prior resume.