I use a big docking station block that allows me yo use 3 monitors with my laptop. At times when a fully Ubuntu system update occurs it breaks the driver. The solution is to either re-install the existing driver or update to a new one.
Follow instructions here from Synaptics
# Download deb repo file and install it
sudo apt install ./Downloads/synaptics-repository-keyring.deb
sudo apt update
sudo apt install displaylink-driver
It should fix itself in realtime without restarting.