Nice to meet you.
I made an application (car<-> controller) that communicates using qtdbus provided by Qt. see. https://doc.qt.io/qt-5/qtdbus-remotecontrolledcar-example.html
Fortunately, I was able to verify that the application's communication was working fine.
But when I use systemd to run the application automatically at system boot, I have a problem with no communication.
Below are the services I wrote.
Controller systemd service
Description=Controller App execution
Car systemd service
Description=Car app execution
my qdbus service
My purpose is to make the two applications using qtdbus work fine when the system boots through systemd.
It seems you are approaching the wrong way now.
What more should I look for?