The problem is probably timing. The instructions on the MSL website should be adjusted so the function script is triggered/managed by systemd to fit into the OS startup and shutdown sequence. Adding dependencies on network being up etc. then become simple.
That sounds good for me, but it does not solve my current problem. I opened a ticket, but MSL told me to use the supportet stable versions of OpenELEC or LibreELEC.
I dont want do downgrade LibreELEC, because the ALPHA version works fine. When its stable I will open an ticket again.
Is there any workaround or idea to restart der network service or nic when there ist no or not the correct IP-Adress in LibreELEC?