Been encountering an 'unknown network error' every 2-3 minutes while watching the World Cup via Chromecast, which means I have to continually close the app and restart the stream. Quick google search and I found out that this issue has been around for TWO YEARS. Seriously? No problem with any other apps streamed to Chromecast, only Optus Sport. I've tried three different devices, and all 3 have the same problems.
I've been getting the exact same error, but only when live streaming. On demand works fine with Chromecast for me. Like you it's happening to me with multiple devices.
Was extremely frustrating having it dropping out constantly during Socceroos match and Argentina match last night. I gave up in the end and finished the Argentina match on demand this morning.
Same issue. It's a disgrace that Optus have purchased the rights to The World Cup and proceed to sell a service to customers that does not work. Greed and incompetence are not a good mix.