I managed to update to LS-CHL today. I have (since I bricked my first Linkstation) used a direct connection to the updated LS, but this new one is different. I only managed to update it within my network.
Another difference is that the lost contacts were possibly because of different NAS Navigator versions. It seems I got rid of lost communications when I uninstalled the older Navigator and installed the one delivered with the LS-CHL.
Let´s see if this was the solution. At least I have been finally able to move some data into it.