Seeing as an annoying Roon issue was solved so easily, here’s another.
I always control by Unifi Star via the Naim app on an iPad. Both units are on wi-fi, both with static local IPs. If the iPad display has gone to sleep and I wake it up again, the Naim “screen” needs to refresh itself once or twice before I can interact with it. Is there any way I can prevent this? The delay in turning down the volume when the phone rings or someone comes in to the room is less than great.
I had a similar issue on Android with the display going to sleep. On Android I found an app that would stop the tablet going to sleep. However if the device is running off battery the issue is rapid battery drain. In my case it’s on a table permanently plugged into the charger - it’s essentially only used as a remote for the player. If I’m honest I’m not 100% convinced that the concept of using an ‘app’ instead of a proper remote control really works.
This effect normally indicates a poor Wifi network, for example the WiFi signal strength at one or both units is on the low side or where there is an ethernet over mains adaptor involved. You could temporarily wire the Star in with an ethernet cable (they are very cheap) and see whether that helps. If it does, then that tells you something.
Why have you got fixed ip addresses? That shouldn’t be necessary at all. Both the Star and iPad are designed to use DHCP.