iOS Sync is still in development/testing phase and not available to public. Not sure how you are testing sync between iOS and desktop. We should have iOS sync rolled out sometime soon.
Important edit: I can also confirm that shutting down brave on my computer and starting over solved the problem. Should have tried that first, but the sync now works for me. AND it merged the bookmarks from each device instead of overwriting. Great feature!
I can confirm that I am getting the same error. Started a sync chain on my phone and am getting a “no internet connection” error on my Mac when I try to sync. Haven’t yet tried to start a chain on my desktop and sync the phone because I don’t want to lose the bookmarks on my phone. I am also connected to the internet with no VPN.
Phone - where I started the chain
GS7 Android 8.0.0
Brave Version 1.0.77
Desktop - where I get the error
Brave Version 0.59.35
OS 10.14.2