First, let me say that this has to be a well known issue. Its seen on different threads on boards but no one seems to be tracking what the solution is and I just see people at slingbox telling users to go to chromecast, and chromecast forums telling us to contact slingplayer.
Let me just say what I know...
I've had a Slingbox 500 for about 3+ years now. Its worked well for me in my home network without issues. This isn't something new introduced to the network or a new firewall or router setting.
Come recently, I tried to connect from my girl's house and cast it to her tv. Slingplayer for android worked in connecting and I saw the video and could perform action the second I tried to pitch it to the chromecast (v1), it said said something about a connect issue and aborted. Again, played fine on my phone but wouldn't go to her chromecast on her tv.
I came home, tried to use my chromecast (v2), and watched it fail. Only mine said nothing about a connection error but instead just froze on the slingplayer splash screen that has the build number.
See video: https://www.youtube.com/watch?v=4gsQTQKe2P4. THIS is what is happened to many people in MANY threads. The fact that I can reproduce this with no variables changing and how its just in the slingplayer app for android leads me to believe that this is a problem with slingplayer app (paid and free version, and phone and tablet versions for android, I've tried all 4).
I called Sling support and they were too eager to tell me I'm SOL and to call support. Support which is $30 and they were quick to tell me that if they couldn't resolve my issue, I'd still be charged. All this for a known issue? The support girl did say that the support team is aware of it but its not something they'd comment on now. Also important to mention that I have no installed new firewall, network issues, rules, etc. Chromecast works fine with all other apps.
First - someone acknowledge this as an issue, then resolve it. Refusing to acknowledge the problem, or refusing to contact/calling me directly to find STEP BY STEP how to reproduce the issue to help solve software shortcomings is sticking your head in the sand and unacceptable. This worked fine up until recently. Is at least android only issue. I don't have an iOS device to test the slingplayer for iOS at this time.