diff --git a/src/services/network-diagnostic.ts b/src/services/network-diagnostic.ts
index 820c110..a377d34 100644
--- a/src/services/network-diagnostic.ts
+++ b/src/services/network-diagnostic.ts
@@ -322,7 +322,7 @@ async function pollGlobalpingResult(id: string): Promise<GlobalpingRawResult[]>
 }
 
 // SNI 차단 시 나타나는 에러 패턴 (한국 ISP DPI)
-const SNI_BLOCK_PATTERNS = ['ECONNRESET', 'connection reset', 'socket hang up'];
+const SNI_BLOCK_PATTERNS = ['ECONNRESET', 'connection reset', 'socket hang up', 'socket disconnected before secure TLS'];
 
 async function checkKoreaProbes(domain: string): Promise<GlobalpingProbeResult[]> {
   // Create 3 measurements in parallel: