Very often it depends on your local network, so it is difficult to give a straight answer. Here are some tips.
In Ticket to Ride, if all players are in the same room AND they all have iOS devices, we recommend using Bluetooth. Make sure Bluetooth is activated on all devices, and check the "iOS devices only" option.
If players have different types of devices (a mix of computers, Android and iOS devices for instance) or are more distant, use the local network (LAN and/or Wifi). For iOS devices, make sure to turn OFF the "Apple devices only" option.