diff --git a/aqt/sync.py b/aqt/sync.py
index fcadf86f7..c54000654 100644
--- a/aqt/sync.py
+++ b/aqt/sync.py
@@ -180,6 +180,8 @@ AnkiWeb is too busy at the moment. Please try again in a few minutes.""")
             return _("Proxy authentication required.")
         elif "code: 413" in err:
             return _("Your collection or a media file is too large to sync.")
+        elif "EOF occurred in violation of protocol" in err:
+            return _("Error establishing a secure connection. This is usually caused by filtering software, or problems with your ISP.")
         return err
 
     def _getUserPass(self):