I performed a firmware update from the dashboard after being informed by email. The update ran and was 90% complte when it ran into and error. Did not make a note of the code, sorry. I retried right afterwards. That one went sooner, but also came to an error. Both errors were caused by a network problem, but there is nothing wrong with my network or the internet access.
After that I went to the Support page and hit the blue button in the lower left column for saving a network problem report. It started up, but now it shows 'Initializing device, please wait'. The picture of the drive in the lower left corner now radiates in yellow. Should be green if I remember well. That message if there for more than an hour now.
I can access the data on the NAS from explorer, but even if I leave the dashboard, when I come back the situation has not changed and the drive is still 'initializing'.
Well...., I gave it another try. Ignoring the initializing message. Just ran the update again for the 3rd time. It worked out. Everything OK now.