Comms TCP/IP failure

[peci1]

In one of our local simulations, we have seen this error in the comms client node:

[rosout][WARNING] 2021-08-22 02:07:00,173: Inbound TCP/IP connection failed: timed out
[rospy.internal][ERROR] 2021-08-22 02:07:00,175: Inbound TCP/IP connection failed:
Traceback (most recent call last):
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/impl/tcpros_base.py", line 325, in _tcp_server_callback
    header = read_ros_handshake_header(sock, StringIO(), buff_size)
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rosgraph/network.py", line 357, in read_ros_handshake_header
    d = sock.recv(buff_size)
timeout: timed out

I assume it is generated by a timeout in the service call from SubT ROS relay when a message is sent to the client. After this error, the comms client did not receive any comms for about a minute (of real time).

I'm not really sure this has a solution, but I wanted to report the error so that other teams have one more place to look at when debugging.