Is there a keyboard shortcut to open the list of networks?

Win + B gets you to the notification area. You could either arrow key over to the icon, or set it as the first icon (from the left).

Then, all you have to do is: Win + B, Enter.

There is no built in way for the Windows but you can do it using AutoHotKey, download it and install it. Now open the notepad and type the following code

^L::Run::{7007acc7-3202-11d1-aad2-00805fc1270e}

and save it with .ahk extension, launch this script by double click on it and now when you will click the Ctrl+L it will open the network connections window.

You can also compile this script after creating it by right click on it which would become a portable exe, just carry it wherever and launch it.

Note: You can change the L key with your preferred key.