Frontview not accessible

I have 2x ReadyNas NVX running the latest software. They've both been installed for a very longtime. One is the primary, accessible via Windows 10 shares, and I have enabled SSH. The primary also runs as a logitech music server(LMS), installed via frontview.

The other is just a backup that does an rsync backup of the media share.

I couldn't get the latest version of the LMS running and was doing some debugging with Michael from Logitech via SSH. I tried starting LMS via SSH and it failed, once with a segment failure, and the second time with a perl compilation error.

I went back to reload a working LMS level via frontview, and it is no longer accessible, even after a reboot.  Chrome reports

This site can’t be reached 192.168.0.2 refused to connect.
ERR_CONNECTION_REFUSED

The shares are still accessible, as is SSH. I tried following the instructions in https://community.netgear.com/t5/Using-your-ReadyNAS-in-Business/No-access-to-Frontview-Duo-V1-running-4-1-6/td-p/1693316

and Apache started, but still not accessible.

I'm guessing when we tried to run the LMS from the SSH shell something got overwritten, or a config file changed.
Apart from doing an OS Restore and resetting the primary readynas does anyone else have any ideas on how to recover this?