ROS2 Distributed Nodes Not Communicating

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ROS2 - FOXY

I have setup two ROS2-Foxy environments with ROS_DOMAIN_ID=0:

1) RaspberryPi 3B+ Ubuntu 20.04 64-bit Server
- - Ubuntu ufw is disabled

2) VMware Fusion running Ubuntu 20.04 64-bit Desktop
- - ROS2 Foxy
- - on Ubuntu 20.04.2 LTS 64-bit Desktop
- - in an 8 GB Ram 3-cores available to VMware Fusion virtual machine
- - on a 32GB 3.2GHz 6-Core Intel Core i7 2018 MacMini
- - running macOS Big Sur 11.0.1
- - Bridged Network Adapter (same if Bridged Ethernet or Bridged WiFi) - - Ubuntu ufw is disabled

• Each system will successfully communicate (localhost) for
  "T1: ros2 run demo_nodes_cpp talker" and
  "T2: ros2 run demo_nodes_py listener"
  (any combination of cpp/cpp, py/cpp, cpp/py, py/py )

• Each system is able to ping to the other

• Both systems ifconfig report

  UP,BROADCAST,RUNNING,MULTICAST

• Multicast test works one way - to the VM

  ROS-VM: ros2 multicast recieve
  Waiting for UDP multicast datagram...
  Received from 10.0.0.11:43044: 'Hello World!'

  ROSbot: ros2 multicast recieve does not succeed

• Both systems have ROS_DOMAIN_ID=0

• Both systems have ROS_LOCALHOST_ONLY=0

BUT when I run a talker on one system and listener on the other, the listener never reports receiving the "Hello World" topic.

On RaspberryPi ROSbot running the talker, "ss -tulw" reports:

pi@ROSbot:~$ ss -tulw
Netid          State            Recv-Q           Send-Q                       Local Address:Port                          Peer Address:Port          Process          
icmp6          UNCONN           0                0                         *%wlan0:ipv6-icmp                                *:*                              
udp            UNCONN           0                0                        0.0.0.0:7400                               0.0.0.0:*                              
udp            UNCONN           0                0                        0.0.0.0:7412                               0.0.0.0:*                              
udp            UNCONN           0                0                        0.0.0.0:7413                               0.0.0.0:*                              
udp            UNCONN           0                0                      127.0.0.1:58641                              0.0.0.0:*                              
udp            UNCONN           0                0                        0.0.0.0:34723                              0.0.0.0:*                              
udp            UNCONN           0                0                  127.0.0.53%lo:domain                             0.0.0.0:*                              
udp            UNCONN           0                0                10.0.0.11%wlan0:bootpc                             0.0.0.0:*                              
tcp            LISTEN           0                4096                   127.0.0.1:45585                              0.0.0.0:*                              
tcp            LISTEN           0                4096               127.0.0.53%lo:domain                             0.0.0.0:*                              
tcp            LISTEN           0                128                      0.0.0.0:ssh                                0.0.0.0:*                              
tcp            LISTEN           0                128                         [::]:ssh                                   [::]:*                              
tcp            LISTEN           0                100                          *:8888                                     *:*

and the ROS2 virtual machine reports:

ubuntu@rosdesk:~$ ss -tulw
Netid  State   Recv-Q  Send-Q                      Local Address:Port              Peer Address:Port  Process  
icmp6  UNCONN  0       0                                       *:ipv6-icmp                    *:*              
udp    UNCONN  0       0                               127.0.0.1:39592                  0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:60176                  0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:7400                   0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:7412                   0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:7413                   0.0.0.0:*              
udp    UNCONN  0       0                           127.0.0.53%lo:domain                 0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:37045                  0.0.0.0:*              
udp    UNCONN  0       0                                 0.0.0.0:631                    0.0 ...