My Roon Core runs integrated within Innuos Zen Mini. Managed after some effort to instal Innuos update to latest version. Afterwards, my Roon Remote devices would not connect with the new Roon 1.8 (laptop running Windows 10, Samsung tablet, Kindle).
Solution was to: uninstall Roon Remote App from the device affected, including any associated data / cache and settings (it may ask you to tick this option during uninstal).
Then, reinstal the Roon Remote App from Google Play Store or similar. In the case of a laptop, this may be reinstal of the appropriate (e.g.) Windows 64-bit operation system for Roon.
Roon should now respond, but will ask you to log back in to your account, and then will re-build your visible database of music as if from scratch. You’ll also need to restore any settings you’d created before.