Leave the "join network" blank.
To set up the mobile client, you first click on your network name, then "add client", then "add mobile client", then you type in a client name and mark the checkbox "networks" to choose your network name.
Then later, you don't fill in the "join" (network id).
To set up the mobile client, you first click on your network name, then "add client", then "add mobile client", then you type in a client name and mark the checkbox "networks" to choose your network name.
Then later, you don't fill in the "join" (network id).