If you try to solve this problem at the level of the file copy tool, rsync is as good as it gets. Be sure to use the options -au, so that rsync won't try to synchronize the same file multiple times. Rsync will make progress as long as it's able to at least exchange the file list and transfer one file fully before being interrupted; if you can't ensure that, you're going to have trouble without a network-level tool.

I think it is easier (and more natural) to solve this at the network level: build a reliable network tunnel on top of your unreliable network connection. Years ago I used Rocks for this very purpose; it's unmaintained and I haven't tried compiling or using it recently, but there's no fundamental reason why it wouldn't work. Watch this space for alternatives.

If you try to solve this problem at the level of the file copy tool, rsync is as good as it gets. Be sure to use the options -au, so that rsync won't try to synchronize the same file multiple times. Rsync will make progress as long as it's able to at least exchange the file list and transfer one file fully before being interrupted; if you can't ensure that, you're going to have trouble without a network-level tool.

I think it is easier (and more natural) to solve this at the network level: build a reliable network tunnel on top of your unreliable network connection. Years ago I used Rocks for this very purpose; it's unmaintained and I haven't tried compiling or using it recently, but there's no fundamental reason why it wouldn't work. Watch this space for alternatives.