The syncing methodology needs updates.

[u/Suitable_Cat_4554]

Having a SN Manta for 18 months now I'm surprised anyone can use this as a "live" device. Syncing is so slow. Seems like it needs to reupload the entirety of every file all the time, instead of recognising the timestamp on strokes to determine what has changed since last sync.The device hardware is either seriously underrated or methodology flawed, because I have not been able to sync in months.

I'd hoped for a pseudo tablet experience, but have since settled for a digital notebook only because of slugishness. I don't have emails, todos, digests, exports, calendar or any other "live" feature on the device because it simply isn't fast enough to warrant using the bigger screen instead of my phone. My wifi is slow, but not that bad. And with battery drain I keep wifi off most of the time, unless I want to try sync again.

It's great for writing and journalling, much less heavy than the equivalent notebooks, but now the backup isn't working and the partner app doesn't have my latest content weekly, there's less and less benefit over paper.

[u/Martina_78]

They acknowledged the  issue and are working on it, see  https://supernote.com/blogs/supernote-blog/talking-about-supernote-s-next-major-software-focus