connectionToServer.hostId == -1 in host mode

Hello Unity community!

I've created a simple prototype where box is moving when user press arrows.
Every 0.1 seconds server sends a message to the client.
On the client side all I want is just print the message delay.
For this purpose I'm using NetworkTransport.GetNetworkTimestamp on the server and NetworkTransport.GetRemoteDelayTimeMS on the client side.
When I start the game as a host in editor using "LAN Host" button, the connectionToServer.hostId property returns -1 instead of valid hostId.
This results in the following error:

Here is my code for retrieving the delay in seconds.

Code (CSharp):

1.     private float GetRemoteDelay(Sync sync)
2.     {
3.         var error = default(byte);
4.         var delay = NetworkTransport.GetRemoteDelayTimeMS(connectionToServer.hostId,
5.             connectionToServer.connectionId,
6.             sync.serverTimestamp,
7.             out error);
8.  
9.         if(error != 0)
10.         {
11.             Debug.Log("Error:" + error);
12.         }
13.  
14.         return delay / 1000f;
15.     }

I've checked NetworkMessage.conn.hostId in the message handler, it's -1 too.
Checked NetworkManager.singleton.client.connection.hostId, it's -1.
What am I doing wrong? How to avoid that? Where to take hostId and connectionId when runnig a host?

Thank you!