Thanks a lot, after this update modbus slave is working perfectly.

Thanks for your quick reply. I already updated the system, that was amogst the first things I tried. So there currently is nothing for apt to update. Nevertheless, I followed your instructions and rand these two commands. As expected, no packages where updated and the issue still remains. /usr/sbin/...

Hello, I have the same problem on a recently bought RevPi Core. Pimodbus-slave doesn't work after a reboot, according to netstat it didn't even open a socket but there is a piModbusSlave process up and running. Systemctl also correctly lists is as active running. Stopping and starting it by systemct...