External monitor not found after Win 10 update

I have a Dell XPS laptop and a circa 2008 Lenovo ThinkVision monitor connected via docking station. The docking station is still working for my mouse, printer, hardwired network connection and speakers, only the monitor is a problem.
Also, I know there's a signal somewhere, because when everything is connected (monitor ==>docking station ==> laptop) the monitor power button is green instead of amber, and the monitor reads Power Saving Mode. When the chain is broken, the power button turns amber and the screen is dark.
When I go into Settings, I see only one monitor. Windows 10 no longer detects an external monitor. This happened immediately after the last major Windows update. Maybe it was a coincidence, I don't know.
I have visited the Lenovo website, there are no drivers for my monitor on it anymore, just a terse listing of features.
To be clear, everything worked and Windows 10 saw my external monitor until this last update. Since then it has not worked. I changed nothing. I have rebooted, plugged and unplugged everything in all imaginable sequences. No joy.

alphanumeric said:

You likely need to reinstall the driver package for the docking station. If its connected via USB it has a USB GPU inside it that uses its own driver. It will also be listed separately under Display Adapters in Device Manager. Its not running off of the laptops GPU. Connect it directly to the HDMI port on the laptop and it will likely work.

I disconnected the docking station and uninstalled the driver, rebooted my laptop and reconnected the docking station. The driver reinstalled and connected my keyboard and mouse, but still no monitor, and now the external speakers aren't working. There is no HDMI port on my laptop. It's super-thin, and HDMI was a casualty. My monitor currently has an 18 pin connector anyway. Maybe it would support HDMI, I haven't needed to try before.