@ira_kaufman, can you post a screenshot of the Roon → Audio tab? Also, is your iPad a WiFi-only model or does it have a mobile network (LTE, 3G) radio in it also? Have you confirmed your iPad is connected to the correct WiFi network in your home? Finally, what version of Roon Core are you using on your Mac Core, and what version is installed on your iPad?
When the remote can’t find the core have you tried pinging the the core machine to check it’s not sleeping?
This occasionally happens to me (& mine is set to Not Sleep) but after a ping it wakes up and works again. As a alternative you could try Wake up on Lan (wol)….