There is eduroam. You can also use
SSID: Amsterdam Science Park
This is an open network. You should see a landing page on which you have to click “connect”.
If you do not see the landing page, here is the url:
http://100.70.0.1:8002/index.php?zone=sp&redirurl=http%3A%2F%2Fmail.surfsara.nl%2F