After you create the subscriber "laser", does it receive any messages from the turtlebot? To determine this, you can check the LatestMessage property, or add a callback function to display the message:
laser.NewMessageFcn = @(~, msg) disp(msg);
If you are receiving messages, you may simply need to increase the timeout. If you are not receiving messages, you can also check with rostopic:
Use Ctrl+C to exit the echo. If that also is not working, then make sure that the turtlebot is actually sending messages. You can do the rostopic echo on one of the Linux terminals on the turtlebot machine to check that.
If messages are being sent, but not received, then there is a connection issue. Make sure that both MATLAB and turtlebot are using the same ROS Master. Also check that the turtlebot is advertising its IP address by setting the ROS_IP environment variable appropriately before launching the turtlebot node. You can also try simpler demos (talker/listener) to see if you can get communication going between MATLAB and the turtlebot machine without involving the complexity of the actual turtlebot.