Cannot exchange data between instances on different machines on a network

[maxikrie]

I have built the ShapesDemo from sources on two different Debian machines, where I had previously installed Fast-DDS as described in https://fast-dds.docs.eprosima.com/en/latest/installation/sources/sources_linux.html#linux-installation-from-sources. I simply used

mkdir build
cd build
cmake ..
make 

for compilation inside the ShapesDemo folder, which is set to follow the master branch (v2.1.0). (I could not try the quick demo since the docker image seems not to be available at https://eprosima.com/index.php/downloads-all.)

When I run two instances of the compiled ShapesDemo app where one publishes on the default Square topic, the data is correctly received on the other app subscribing to this topic. However, when I try the same experiment on two different machines connect over LAN, no data on this topic is received on the subscriber side. Pinging between the two machines works and I have checked wireshark for data exchange. It seems that there is some data exchange going on (192.168.0.99 is publisher, 192.168.0.82 is subscriber), however the actual topic data doesn't seem to be sent at all? Below a screenshot of wireshark executed on the subscriber side:

[maxikrie]

Just for reference - this is the wireshark output when both ShapeDemo instances run on the same machine and data is correctly received on the subscriber:

Even though this works correctly, shouldn't I expect some kind of data package every 75 ms at which the Square topic is updated by the publisher?

[maxikrie]

There was a firewall issue on the subscriber (ufw), which blocked incoming traffic from publisher. It works now!