Hi @nirmo2112! If these were linked before, nothing should have caused them to be unlinked unless a device was reset, newly setup, or removed from the app. Please double check the locations drop down in the Ring app to ensure these devices don’t show as linked on another address, or that these are both on your account as the owner. Please also confirm these are not linked in a light group.
Once confirmed, everything should be optimal for you to link these devices as desired. I recommend optimizing mobile device connection by disabling bluetooth and VPN, as well as trying this while connected to wifi only, or data only, to see if there is a difference in operation. If this concern persists, try removing and reinstalling the Ring app on your mobile device. I hope this helps!