First, you can check the Seafile client log (
~/.ccnet/logs/seafile.log for Linux,
C:/users/your_name/ccnet/logs/seafile.log for Windows) to see what's wrong.
Firewall: Ensure the firewall is configured properly. See Firewall Settings for Seafile Server
Set environment variable
SEAFILE_DEBUG = all before running Seafile client. On Linux, you can open a terminal and type: