The app is just a remote to the system. Either your phone isn’t connecting well enough to the system, or the system isn’t connection well enough to your WiFi. This could be either be your phone, or the system, or your WiFi.

I had a problem with slow connection for a long time - music selection taking 10 seconds plus to register, seeing the spinning wheel, group changes not taking effect or taking a very long time to do so. Then, yesterday I had a call with someone on the support line and he happened to mention that he could see my guest wi-fi network looked like it was causing interference; so, as it’s rarely in use I turned it off. Since then it’s been pretty much as smooth as it can be, for over 24 hours, so I’m hoping that was what was causing interference. Worth a try for anyone experiencing connection issues.