Push Notifications not working over WiFi on Google Devices I have 3 Android devices at home: Nexus 4 Android 5.1.1, Nexus 5 Android 5.1.1 and Lenovo Yoga 2 Android 4.4.2, all connected to my WiFi. The Nexus devices simply cannot receive Push Notifications (Gmail, Hangouts...GCM?) while the Yoga tablet can. On mobile data both Nexus devices can receive push notifications. If I connect them to my workplace WiFi everything is fine.

All devices have all the apps up to date. I've tried resetting the Nexus 5 to the factory defaults but it doesn't help. I've tried restarting the phones a couple of times but still no luck. The router is an ASUS AC68U, latest Merlin, on a 1Gbps internet connection. The only things that changed in my environment in the past 2 weeks are: 5.1.1 update and I moved to 1Gbps internet.

Is this related to the new Play Services Update? Or Android 5.1.1? Can I somehow look deeper into this? Logcat? Any help is appreciated.
It looks like GCM Push Notifications don't work with IPv6. I disabled IPv6 entirely in my router and now everything is fine. Though IPv6 was enabled for the past two years and I didn't have any kind of issue. Let's hope a Play Services update fixes it.