IOS photo/video backup methodology?

[Enquiries]

My iPhone automatically backs up its photos and videos to the Amazon photo storage that is part of Prime. That works well but I'm about out of storage space (5GB) for videos (photo storage is unlimited). I don't backup my phone's photos and videos to iCloud, since that would quickly exceed the 5GB that Apple gives me. I have both a new Synology DS920+ and an old DS213j with lots of available storage.

I would like to mimic how Amazon's photo and video storage operates on my iPhone, except use one of my Synology NAS units as the "cloud." Is there a practical and effective way to do that with just my iPhone and the NAS device? Or would I be better off figuring out how to copy all the videos I have stored in Amazon Prime's 5GB to my NAS and then delete them all from the Amazon cloud to free up another 5GB for new video storage? And, when I get back to another 5GB stored on Amazon, rinse and repeat?

Based on my reading, I haven't seen anything that works directly between the iPhone and Synology NAS that appears as seamless as how the iPhone and Amazon storage function together (backing up all new files essentially automatically with little or no manual effort). Thanks for your assistance and any suggestions.

[ed]

Yes, Synology Moments or Photos app will automatically sync your multimedia with your NAS. It can be even a cheap J series NAS.Choosing Play or plus series will also allow you to use it for many other purposes than simple backing up.Amazon sync with Synology has been disabled now. So you would need to transfer data manually. But 5GB should not take long.I hope this helps.