NV+ - No fileshares - no frontview

I have a NV+ with 4 2TB disk.

I haven't used it for 6 months and I suddenly became aware of that none of my network shares were available. After some investigation I found that this was not the only thing not working.

I'm not gonna say that "I have no backup!!!!", because I think I do, at least of the most critical stuff (family pics and videos), but I still have 4TBs of other data on these drives I would like to keep (or else I wouldn't post here :-) ).

The good:

• The NAS seems to boot fine, going through quota-check and ending up displaying the IP. All LEDs are OK.
• The IP is pingable
• The RAIDar sees the NV+ and gives green lights on all disks, fans and temp. Disk models, usage and temperatures are displayed.
• In the Win10 network overview my NAS appears as a storage device and media device. However, clicking on the icons is a dead end.

The bad:

• Frontview is unavailable (says "connecting" for a while and then times out . ERR_CONNECTION_TIMED_OUT)
• No file shares are available
• No SSH or Telnet available (as I've understood from reading this would have to be enabled in frontview (which it hasn't))
• FTP isn't working

The strange:

• When pinging, I get at 1ms response time 4/5 times, but every 5th ping has a delay ranging from 100ms to "Request timed out"
• On the front of the NV+, all disk LEDs are solid green (no blink). Every few seconds the "act" light blinks, followed by the blue power button pulsating 5-6 times. Then a short break, before the "act" LED blinks again and the cycle repeats. I've not been able to find out if this corresponds with the prolonged ping-reply. I've neither found any match in the "led-language-list" for the NAS.
• Some times, a while after boot, RAIDar looses sight of the NAS and can't find it again before i reboot the NAS. (The ping still works though)

Other info:

• I've done the OS reset. This succeedes, but there seems to be no change after it completes.
• The NV+ frontview has always been sloooooow. My initial thought when it wasn't working was that "something" has made the NV+ so slow that it doesn't respond (fast enough).
• Maybe no need to say, but multiple resets and powering the unit down for a day etc. have been tried.
• Altough I've not been using the NAS, my dlink ipcams have. They upload images on any movement from my back porch or garage through ftp to the nas. (which can be 100-1000 files a day, not that much isolated, but over the course of a year it's quite a few.) 

I've read about USB boot and TFTP boot, but the instructions are usally preceeded by "don't do this unless instructed to by netgear support".

I'm not sure if I'm a few years to late to get any hints or tips regarding this unit, but any help is appreciated.