It's handy to have GUIs for your ROS applications, but QT applications run a bit differently with ROS. They must be run in a multithreaded execution to work properly.
The following example shows my workflow for using a QT gui (with an external ui file) in a ROS node:
# An example interface node for the gui
import rclpy
from rclpy.node import Node
For communication between wifi and ethernet devices, the DDS layer in ROS2 relies on the multicast ability of a given network.
This is often disabled on enterprise networks (at university or work etc) for (I think) security reasons .
To get around this, you have to configure CycloneDDS to comunicate in a unicast manner, and you must specify the local IPs of all the participants you want to communicate.
_I am using CycloneDDS instead of the default (for ROS2 humble at least) FastDDS, because I ran into lots of issues trying to get topic