PROBLEM SOLVED !
I wanted to share my experience and solution in case anyone else has this problem. The bottom line is DON'T USE AN IPAD WITH TIDAL CONNECT !
The tidal app for ipad is distinct from the iphone or Android apps. The ipad app does not show the ZS as an direct output device, so it was using airplay to connect Tidal to the ZS. This bypasses the native ZS connection to Tidal and causes myriad issues with navigation, drops, etc... Not to mention lower SQ.
After messing up my router fooling with static DNS addresses, and 2 weeks of other misguided efforts, I'm now successfully using the ZS and enjoying the nice SQ. Not a slick interface, but it now WORKS.
Thanks to all (and ifi, in spite of criticisms of their support) offering their help