FAQ - Garfonso/SyncML GitHub Wiki

Question: Will the connection to the SyncML server be encrypted? Or is going thru a VPN the only option to achieve that?

You enter the URL of your SyncML Server in the app. If you enter a URL starting with HTTPS the connection will be encrypted. Of course the server needs to provide a HTTPS connection and the certificate also needs to be valid. I have a self signed certificate on my private web-server that I use with eGroupware for SyncML and encryption in the app works fine. For the self signed certificate to work, I need to visit the HTTPS-URL of my server once in the device's browser and select to accept the certificate for ever, though. The app itself can't ask that, as it seems. In fact it doesn't know anything about encryption or whether it fails. So if you get the message "Got empty response" (it get's buried in the logs somewhere, sadly. Need to clean that up), then something with the connection is broken. If connection to the server basically is working, then the certificate might be the issue.

If your server does not offer HTTPS, then VPN is the only option left. But I have no experience with that.