Just to clarify what happened here, in case a future reader of this thread is puzzled by this. I interpreted your earlier comment:
Connect it to a computer with the USB cable and you have a network.
as meaning that at some level something usable would start up automatically when connecting the L5 to my computer by USB. When it didn’t, I tried to set up the network by setting a static IPv4 address on the L5, and intended to do the same for the USB interface on my computer (since that doesn’t require installing and configuring a DHCP server). It was that step that I couldn’t do in the settings app, because that part hasn’t been adapted for the L5’s screen size. Sorry for any confusion.
I run Gnome on my desktop and laptop, and I don’t know what would be different if I was running Plasma instead.