diff --git a/app/src/main/java/ca/pkay/rcloneexplorer/Rclone.java b/app/src/main/java/ca/pkay/rcloneexplorer/Rclone.java
index b21b771b5..458905f71 100644
--- a/app/src/main/java/ca/pkay/rcloneexplorer/Rclone.java
+++ b/app/src/main/java/ca/pkay/rcloneexplorer/Rclone.java
@@ -691,9 +691,24 @@ public Process sync(RemoteItem remoteItem, String localPath, String remotePath,
         ArrayList<String> defaultParameter = new ArrayList<>(Arrays.asList("--transfers", "1", "--stats=1s", "--stats-log-level", "NOTICE", "--use-json-log"));
         ArrayList<String> directionParameter = new ArrayList<>();
 
-        if(useMD5Sum){
+        boolean isSftpRemote = remoteItem.isRemoteType(RemoteItem.SFTP);
+        if(useMD5Sum && !isSftpRemote){
             defaultParameter.add("--checksum");
         }
+        if(isSftpRemote){
+            // Many SFTP servers (e.g. Synology restricted shells) can't run md5sum/sha1sum
+            // over SSH even though the files are reachable via SFTP. Disabling the remote
+            // hash commands avoids "corrupted on transfer: hashes differ" failures, but it
+            // also means no common hash type is left to compare with --checksum. If both
+            // were combined, rclone silently falls back to a size-only comparison and
+            // ignores modification time, so changed files of the same size never get
+            // re-synced. Skip --checksum here and let rclone use its default size+modtime
+            // comparison instead.
+            defaultParameter.add("--sftp-md5sum-command");
+            defaultParameter.add("none");
+            defaultParameter.add("--sftp-sha1sum-command");
+            defaultParameter.add("none");
+        }
         if(deleteExcluded){
             defaultParameter.add("--delete-excluded");
         }