I purchased the original Chromecast the day it was released. No problems ever.
Upgraded to Chromecast 2015 and I can't set it up.
Here's my setup:
Samsung S3 4.4.2
Dlink AC3200 Ultra Wi-Fi Router DIR-890L/R - no firmware update available
Lemon Chromecast 2 or 2015 - whatever they are...