Multiple machines - nodes somewhat communicating

edit

I am trying to get a navigation stack running on an Lego NXT-based system. However, it is different from the normal nxt_apps assisted_teleop in that the NXT is carrying a camera and a laptop, which is doing some of the navigation and SLAM processing (so I don't have to send camera images over the network), and another computer, which is running rviz and the rest of the vslam and navigation stacks. I am having trouble seeing messages from one computer on another. I have read the ROS troubleshooting page for network configuration, and I have done everything it says. Here is my roswtf output:

 Beginning tests of your ROS graph. These may take awhile...
 analyzing graph...
 ... done analyzing graph
 running graph rules...
 ... done running graph rules

 Online checks summary:

 Found 2 warning(s).
 Warnings are things that may be just fine, but are sometimes at fault

 WARNING The following node subscriptions are unconnected:
  * /base_ctrl:
    * /joint_states

 WARNING The following nodes are unexpectedly connected:
  * /joy_node->/rosout (/rosout)


 Found 7 error(s).

 ERROR Communication with [/rosout] raised an error: 
 ERROR Communication with [/camera_tf] raised an error: 
 ERROR Communication with [/nxt_teleop] raised an error: 
 ERROR Communication with [/base_ctrl] raised an error: 
 ERROR Communication with [/camera] raised an error: 
 ERROR Communication with [/nxt_ros] raised an error: 
 ERROR The following nodes should be connected but aren't:
  * /base_ctrl->/nxt_ros (/joint_command)
  * /nxt_teleop->/base_ctrl (/cmd_vel)
  * /joy_node->/nxt_teleop (/joy)

Here is my 'rostopic list' output:

 /camera_info
 /cmd_vel
 /diagnostics
 /image_raw
 /joint_command
 /joint_states
 /joy
 /rosout
 /rosout_agg
 /tf

These commands were run on the second computer, the one which is not the laptop. If I run these commands on the laptop, they report completely normal results.

If it's of any interest, roscore is running on the computer which is not the laptop. Also, no firewalls are running on either computer.

What is happening here?