1. I installed VNC Viewer on my Ubuntu from here. Then, I could connect to my Raspberry PI by both hostname and IP address.
  2. However, I can't do the same from my Samsung Note 8 I can't connect by hostname - I'm getting something like "Cannot resolve hostname". If I use the IP address then I don't have any problem.

Ubuntu PC, Samsung Note 8 and Raspberry PI3 are all connected to the same WIFI network.

Can someone explain what is wrong here?