Sounds like your dealer needs to find the problem and resolve it. As Msgreenf mentioned changing the DNS to Google is step one, second step should be for your dealer to verify the correct time zone is set on your controller, third IPV6 if its on in your router can cause issues with music streaming or buffering, this should be turned off but you need to log into the router to accomplish this. Lastly if you’re using your internet service provider’s combo router I would recommend getting rid of it. Combo routers cause network issues within a C4 system. I would get a separate router and a separate modem to run your network. I hope this helps but your dealer should already know to try these steps out to resolve your issues.