Google Nexus 6 :: Any Way To Prioritize WiFi Networks?

I got a problem where 2 different wifi networks are available and my N6 is switching between them all the time. Not only does this drain the battery but the other network must be certainly weaker, as the router is far away. In reality this means, that my phone is sometimes 20 sec. without any connection as it tries to switch back and forth. I don't know, why the phone still tries to switch to the network, my guess is that because the weaker network is a certificate-installed (university) network and thus is prioritised. However, is there any way to manage prioritization in lollipop? I know that this was possible in iOS (and also my Mac which had the problem before) and according to my research this was also a possibility in KitKat.