Hi @daniel.pan,
Can I set “allowed” WLAN SSIDs for syncing with the seafile server, for example “eduroam”? I don’t want to sync big data over an expensive WLAN or mobile account. Or do you have a better solution (third party )for this problem?
Thanks.
You can block Seafile connection (ports) on OS level when you are on some SSID, I’m sure there is some OS level setup or 3rd party apps. Better is just stop client 
The best solution would be if the client would honor the windows setting. Windows has an option to say a wifi network is paid per use and it would be the best to not sync on such networks as long as the change is not less than a few kilobytes (manual synchronization should ask with a dialog).
I now use the Windows Firewall to block the synchronization in public areas.