Hyperbackup is a backup system provided by Synology on their Diskstation and Rackstations and its a good product as is the hardware, but like most things in Synology, the term "set it and forget it" does not apply as this customer found out to their detriment.
The Synology NAS system has a web interface, which is in fact very good and well designed, it allows amongst other things for you to setup an SSL certificate to encrypt web traffic. This can be a self signed, purchased or lets-encrypt certificate and in the latter the process of renewal is automated which is nice.
The problem comes when your SSL Certificate changes, which is would normally do annually for a purchased cert or every 90 days for lets-encrypt, at which point everything breaks including Hyperbackup and the cause isn't immediately clear. The dialogue above indicates that the destination for your backup is offline, you would of course check the backup server and find it online and running. You would check the firewall settings, probably restart the services maybe even reboot the server but nothing is going to make this work again until you go into settings and get as far as target at which point you notice...
Yes, seriously, because your certificate renewed and even though you've specifically not enabled transfer encryption the backup process crashes to a halt. You are required to press "Trust Server Certificate" to continue after which the backup will resume until the next certificate change (90 days for lets-encrypt, a year for purchased). Why? What possible purpose can there be to halting the backup every time a certificate renews? and why is there no way to prevent it?
Just as a side note, other things that break are all the iOS applications, Cloud-Station Backup, Cloudstation, and probably more. If you are going to use a lets-encrypt certificate, and I would encourage you to do so, then every 90 days you need to make a note in your diary to go to all the servers and click all the buttons or stuff will stop working.
Addendum: Just had another customer today who's had a volume crash and his hyper backup stopped working for this very reason about 6 months ago so we're now in the position where he's shipping the unit back to us and we're going to have to attempt volume recovery. PLEASE CHECK YOUR HYPERBACKUP IS RUNNING REGULARLY OR USE ANOTHER BACKUP PRODUCT
Update 20/04/2018 - Yet another customer lost data thanks to Hyperbackup and lets encrypt certificates. This issue is not fixed in the 6.2 beta so we now have no choice but to advise all our customers *NOT* to use Hyperbackup and instead migrate to alternatives. We're already testing a number of alternative products hosted on and off the NAS and will post a full review and recommendations in the near future. If you've come here because your Hyperbackup silently stopped backing up your data then I suggest you also look for reliable alternatives.
Update 09/09/2018 - Another large customer suffers data loss due to this ridiculous situation. We are now removing Hyperbackup from all our customers and replacing it with proper backup software (Retrospect, Backup Exec depending on environment). Please DO NOT use Hyperbackup and rely on it to actually make backup's without daily monitoring.