Ethernet Problems with Lenovo USB-C Dock

For my two ThinkPads I have a Lenovo USB-C dock. And that has the strangest effect on the wired network and disrupts other devices.

Generally speaking a wired connection is always better than a wireless one regarding regarding the signal. So ideally I would like to make use of the dock's Ethernet connection. And I did this the first couple of months.

When I had the dock connected to my work laptop and put it into suspend, all other devices in the same Ethernet switch would lose connectivity. The wireless connections directly to the router were not affected. It seems that somehow the dock broadcasts things that irritate the switch.

I haven't diagnosed this in detail. But I just tried to use the wireless connection for three laptops and disconnected the dock from Ethernet. And this problem was then gone for good. So I've no idea what the problem is, but this will get rid of the symptoms.