diff --git a/server/i18n/src/commonMain/moko-resources/values/base/strings.xml b/server/i18n/src/commonMain/moko-resources/values/base/strings.xml
index 0e599ff49..1671f1c01 100644
--- a/server/i18n/src/commonMain/moko-resources/values/base/strings.xml
+++ b/server/i18n/src/commonMain/moko-resources/values/base/strings.xml
@@ -50,6 +50,7 @@
     <!-- OPDS errors -->
     <string name="opds_error_manga_not_found">Series with ID %1$d not found.</string>
     <string name="opds_error_chapter_not_found">Chapter with index %1$d not found.</string>
+    <string name="opds_error_chapters_not_found">No chapters found or the source is unreachable on page %1$d.</string>
 
     <!-- OPDS facets (Filters and Sorting) -->
     <string name="opds_facetgroup_sort_order">Sort Order</string>
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/sync/KoreaderSyncService.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/sync/KoreaderSyncService.kt
index a0ca9db8a..cbb47f81b 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/sync/KoreaderSyncService.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/sync/KoreaderSyncService.kt
@@ -127,29 +127,36 @@ object KoreaderSyncService {
             }
 
             val mangaId = chapterRow[ChapterTable.manga].value
+            val isDownloaded = chapterRow[ChapterTable.isDownloaded]
             val checksumMethod = serverConfig.koreaderSyncChecksumMethod.value
 
             val newHash =
                 when (checksumMethod) {
                     KoreaderSyncChecksumMethod.BINARY -> {
-                        logger.debug { "[KOSYNC HASH] No hash for chapterId=$chapterId. Generating from downloaded content." }
-                        try {
-                            // Always create a CBZ in memory if it doesn't exist
-                            val (stream, _) = ChapterDownloadHelper.getArchiveStreamWithSize(mangaId, chapterId)
-                            // Write the stream to a temp file for partial hashing
-                            val tempFile = File.createTempFile("kosync-hash-", ".cbz")
+                        // Only generate binary hash if the chapter is downloaded to avoid fetching missing files
+                        if (isDownloaded) {
+                            logger.debug { "[KOSYNC HASH] No hash for chapterId=$chapterId. Generating from downloaded content." }
                             try {
-                                tempFile.outputStream().use { fos ->
-                                    stream.use { it.copyTo(fos) }
+                                // Always create a CBZ in memory if it doesn't exist
+                                val (stream, _) = ChapterDownloadHelper.getArchiveStreamWithSize(mangaId, chapterId)
+                                // Write the stream to a temp file for partial hashing
+                                val tempFile = File.createTempFile("kosync-hash-", ".cbz")
+                                try {
+                                    tempFile.outputStream().use { fos ->
+                                        stream.use { it.copyTo(fos) }
+                                    }
+                                    // Use the same hashing method as for downloads
+                                    KoreaderHelper.hashContents(tempFile)
+                                } finally {
+                                    // Always delete the temp file
+                                    tempFile.delete()
                                 }
-                                // Use the same hashing method as for downloads
-                                KoreaderHelper.hashContents(tempFile)
-                            } finally {
-                                // Always delete the temp file
-                                tempFile.delete()
+                            } catch (e: Exception) {
+                                logger.warn(e) { "[KOSYNC HASH] Failed to generate archive stream for chapterId=$chapterId." }
+                                null
                             }
-                        } catch (e: Exception) {
-                            logger.warn(e) { "[KOSYNC HASH] Failed to generate archive stream for chapterId=$chapterId." }
+                        } else {
+                            logger.debug { "[KOSYNC HASH] Skipping binary hash for chapterId=$chapterId because it is not downloaded." }
                             null
                         }
                     }
@@ -175,7 +182,7 @@ object KoreaderSyncService {
                 }
                 logger.info { "[KOSYNC HASH] Generated and saved new hash for chapterId=$chapterId" }
             } else {
-                logger.warn { "[KOSYNC HASH] Hashing failed for chapterId=$chapterId." }
+                logger.warn { "[KOSYNC HASH] Hashing failed or skipped for chapterId=$chapterId." }
             }
             newHash
         }
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/opds/impl/OpdsFeedBuilder.kt b/server/src/main/kotlin/suwayomi/tachidesk/opds/impl/OpdsFeedBuilder.kt
index 6451a23cb..41c505190 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/opds/impl/OpdsFeedBuilder.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/opds/impl/OpdsFeedBuilder.kt
@@ -644,6 +644,16 @@ object OpdsFeedBuilder {
                 skipMetadata,
             )
 
+        // Return a not-found feed if all available chapters are filtered out as unreachable
+        if (skipMetadata && chapterEntries.isEmpty() && totalChapters > 0L) {
+            return buildNotFoundFeed(
+                baseUrl = baseUrl,
+                locale = locale,
+                idPath = "series/$mangaId/chapters",
+                title = MR.strings.opds_error_chapters_not_found.localized(locale, pageNum),
+            )
+        }
+
         // If no chapters are found in the database, attempt to fetch them from the source.
         if (chapterEntries.isEmpty() && totalChapters == 0L) {
             try {
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/opds/repository/ChapterRepository.kt b/server/src/main/kotlin/suwayomi/tachidesk/opds/repository/ChapterRepository.kt
index df7ca43ea..7b9599ffd 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/opds/repository/ChapterRepository.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/opds/repository/ChapterRepository.kt
@@ -169,6 +169,8 @@ object ChapterRepository {
                     }
                 }
             }.awaitAll()
+                // Exclude unreachable chapters that are not downloaded and have no page count
+                .filter { it.downloaded || it.pageCount > 0 }
 
         return Pair(enrichedChapters, totalCount)
     }