Update to 3.9 (?) killed my Rockstor NAS

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Brief description of the problem

After Update - No GUI or Route To Host
[write here]

Detailed step by step instructions to reproduce the problem

I ran the update script, the on-screen message said (in essence) “updating, manually frefresh page”
I came back an hour later and Firefox reported that there was a problem loading the page.
I opened up the router and the NAS which normally lives at 192.168.20.* is shown as idle (or not connected)
So I did a forced reboot to try and get the server to reconnect to the network - nothing.
No amount of re-powering up the machine does anything, it’s almost as if the update wiped out the OS.

Web-UI screenshot

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Error Traceback provided on the Web-UI

Hah !!

I opened a terminal and pinged 192.168.20.* and …

“Destination Host Unreachable”