Hi, Falco and thanks for the suggestions.
For a couple of months I actually rsync running, but it stopped working for no reason I could ever identify. No errors in logs, no changes I knew of to router, no shortage of hard drive space. Power cycling NAS and router had no effect. Possibly something changed with Digital Ocean, or Discourse software updates - but I am no IT boffin, and my continued attempts at getting to the bottom of this issue just kept being put off by other life priorities.
I have since reformatted and reconfigured the NAS device (due to an unrelated issue), but when confronted with the task of re-learning everything that I had had to research the first time, and all the trial and error involved in trying to get remote backups working the first time, found myself wondering why this should even be necessary.
Delving in to crontabs seems like a similar problem (whatever these are - I assume something like the cron jobs that I once used for backing up from my web host - until they too stopped working for reasons I could never explain or solve).
A good backup system is one that the user is willing and able to sustain.
One that requires knowledge and skills in 3rd party systems that are otherwise not part of the userâs normal range of activities just seems like a weak point, adding more variables and risks than necessary.
By following the guides, I am simply repeating instructions by rote, but with no understanding, and am completely lost if and when things encountered inevitably are not quite as they were for whoever authored the guides.
Any system relying on 3rd party plugins that are no longer even actively maintained, and that are already partially broken also seems like bad idea.
A system where configuration is done all in one familiar place within software designed with this specific task in mind and maintained by people who know a lot more about what is required to achieve the task than I ever will just seems like a better idea to me.