diff --git a/app/src/main/java/com/medithings/vesiscan/ble/BleManager.kt b/app/src/main/java/com/medithings/vesiscan/ble/BleManager.kt
index 7bc534b..b76fc8d 100644
--- a/app/src/main/java/com/medithings/vesiscan/ble/BleManager.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ble/BleManager.kt
@@ -201,6 +201,10 @@ class BleManager private constructor(private val context: Context) {
      *  ClinicalHome 등에서 "BLE Connecting…" 표시용. */
     val isConnecting = mutableStateOf(false)
     val connectionError = mutableStateOf<String?>(null)
+    /** 마지막으로 GATT status=5 (bond mismatch) 로 실패한 device 주소.
+     *  FW allowlist 1:1 bond 정책에서 다른 central 이 붙어 있는 경우 발생.
+     *  UI 가 이 값 non-null 시 "본딩 초기화" action 을 노출. 성공/타 에러로 clear. */
+    val bondConflictAddress = mutableStateOf<String?>(null)
 
     // Callbacks
     var onConnectionStateChanged: ((Boolean) -> Unit)? = null
@@ -1145,7 +1149,17 @@ class BleManager private constructor(private val context: Context) {
                         scheduleAutoReconnect()
                     } else {
                         isReconnecting.value = false
-                        connectionError.value = "Connection failed (status $status). Try again."
+                        // GATT status=5 (INSUFFICIENT_AUTHENTICATION) — FW allowlist 정책상
+                        //   다른 central 과 이미 bond 중이면 peripheral 이 인증 거부.
+                        val failedAddr = gatt.device.address
+                        if (status == 5) {
+                            bondConflictAddress.value = failedAddr
+                            connectionError.value = "BOND_CONFLICT:$failedAddr"
+                            debugLogger.warn("BOND_CONFLICT addr=$failedAddr — FW allowlist rejected (status 5)")
+                        } else {
+                            bondConflictAddress.value = null
+                            connectionError.value = "Connection failed (status $status). Try again."
+                        }
                     }
                     return@post
                 }
@@ -1157,6 +1171,7 @@ class BleManager private constructor(private val context: Context) {
                         isConnecting.value = false
                         isUserDisconnect = false
                         connectionError.value = null
+                        bondConflictAddress.value = null   // 연결 성공 시 클리어
                         val idx = discoveredDevices.indexOfFirst { it.address == gatt.device.address }
                         if (idx >= 0) discoveredDevices[idx] = discoveredDevices[idx].copy(isConnected = true, isConnecting = false)
                         isConnected.value = true
diff --git a/app/src/main/java/com/medithings/vesiscan/ui/views/connection/DeviceScanView.kt b/app/src/main/java/com/medithings/vesiscan/ui/views/connection/DeviceScanView.kt
index 2193dfe..03fcaa8 100644
--- a/app/src/main/java/com/medithings/vesiscan/ui/views/connection/DeviceScanView.kt
+++ b/app/src/main/java/com/medithings/vesiscan/ui/views/connection/DeviceScanView.kt
@@ -68,6 +68,7 @@ fun DeviceScanView(appState: AppState) {
     val isScanning by bleManager.isScanning
     val bluetoothEnabled by bleManager.bluetoothEnabled
     val connectionError by bleManager.connectionError
+    val bondConflictAddress by bleManager.bondConflictAddress
 
     // BLE permissions
     val requiredPermissions = remember {
@@ -225,22 +226,55 @@ fun DeviceScanView(appState: AppState) {
             Spacer(modifier = Modifier.height(8.dp))
         }
 
-        // Connection error
-        connectionError?.let { error ->
-            Row(
+        // Connection error — GATT status=5 (bond conflict) 시 별도 UX 안내 + reset action.
+        val curError = connectionError
+        val curBondAddr = bondConflictAddress
+        if (curError != null) {
+            val isBondConflict = curError.startsWith("BOND_CONFLICT:") && curBondAddr != null
+            Column(
                 modifier = Modifier
                     .fillMaxWidth()
                     .padding(horizontal = 24.dp)
                     .clip(RoundedCornerShape(12.dp))
                     .background(Color.Red)
-                    .padding(12.dp),
-                verticalAlignment = Alignment.CenterVertically
+                    .padding(12.dp)
             ) {
-                Icon(Icons.Default.Close, stringResource(R.string.device_scan_error_desc), tint = Color.White)
-                Spacer(modifier = Modifier.width(12.dp))
-                Text(error, color = Color.White, fontSize = 13.sp, modifier = Modifier.weight(1f))
-                IconButton(onClick = { bleManager.connectionError.value = null }) {
-                    Icon(Icons.Default.Close, stringResource(R.string.device_scan_dismiss_desc), tint = Color.White.copy(alpha = 0.8f))
+                Row(verticalAlignment = Alignment.CenterVertically) {
+                    Icon(Icons.Default.Close, stringResource(R.string.device_scan_error_desc), tint = Color.White)
+                    Spacer(modifier = Modifier.width(12.dp))
+                    val displayText = if (isBondConflict)
+                        stringResource(R.string.ble_error_bond_conflict)
+                    else
+                        curError
+                    Text(displayText, color = Color.White, fontSize = 13.sp, modifier = Modifier.weight(1f))
+                    IconButton(onClick = {
+                        bleManager.connectionError.value = null
+                        bleManager.bondConflictAddress.value = null
+                    }) {
+                        Icon(Icons.Default.Close, stringResource(R.string.device_scan_dismiss_desc), tint = Color.White.copy(alpha = 0.8f))
+                    }
+                }
+                if (isBondConflict && curBondAddr != null) {
+                    Spacer(modifier = Modifier.height(6.dp))
+                    OutlinedButton(
+                        onClick = {
+                            bleManager.unbondAndRemoveAddress(curBondAddr)
+                            bleManager.connectionError.value = null
+                            bleManager.bondConflictAddress.value = null
+                            android.widget.Toast.makeText(
+                                context,
+                                context.getString(R.string.ble_toast_bond_removed),
+                                android.widget.Toast.LENGTH_LONG,
+                            ).show()
+                        },
+                        colors = ButtonDefaults.outlinedButtonColors(
+                            contentColor = Color.White,
+                        ),
+                        border = androidx.compose.foundation.BorderStroke(1.dp, Color.White),
+                        modifier = Modifier.align(Alignment.End),
+                    ) {
+                        Text(stringResource(R.string.ble_action_reset_bond), fontSize = 12.sp)
+                    }
                 }
             }
             Spacer(modifier = Modifier.height(8.dp))
diff --git a/app/src/main/res/values-ko/strings.xml b/app/src/main/res/values-ko/strings.xml
index 5a105e0..015df0e 100644
--- a/app/src/main/res/values-ko/strings.xml
+++ b/app/src/main/res/values-ko/strings.xml
@@ -379,6 +379,10 @@
     <string name="device_scan_pairing_required_title">페어링 필요</string>
     <string name="device_scan_pairing_required_msg">블루투스 페어링 요청이 표시됩니다.\n\'페어링\' 을 누르고, PIN 이 나타나면 입력하세요.</string>
     <string name="device_scan_pairing_required_err">페어링이 필요합니다. 기기를 페어링해주세요.</string>
+    <!-- FW allowlist bond conflict (GATT status=5) — 2026-08-04 -->
+    <string name="ble_error_bond_conflict">이 기기는 다른 앱과 이미 페어링되어 있습니다. 기기 전원 버튼을 15초 롱프레스로 본딩 정보를 삭제한 뒤 다시 시도하세요.</string>
+    <string name="ble_action_reset_bond">이 폰의 본딩 정보 초기화</string>
+    <string name="ble_toast_bond_removed">본딩 정보 삭제 완료. 다시 연결을 시도하세요.</string>
     <string name="device_scan_back_desc">뒤로</string>
     <string name="device_scan_warning_desc">경고</string>
     <string name="device_scan_error_desc">오류</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index fe32a1e..7c06ef3 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -379,6 +379,10 @@
     <string name="device_scan_pairing_required_title">Pairing Required</string>
     <string name="device_scan_pairing_required_msg">A Bluetooth pairing request will appear.\nTap \'Pair\', then enter PIN if prompted.</string>
     <string name="device_scan_pairing_required_err">Pairing required. Please pair the device.</string>
+    <!-- FW allowlist bond conflict (GATT status=5) — 2026-08-04 -->
+    <string name="ble_error_bond_conflict">This device is already paired with another app. Long-press the device power button for 15 seconds to clear its pairing, then try again.</string>
+    <string name="ble_action_reset_bond">Reset Pairing (this phone)</string>
+    <string name="ble_toast_bond_removed">Pairing info removed. Please try connecting again.</string>
     <string name="device_scan_back_desc">Back</string>
     <string name="device_scan_warning_desc">Warning</string>
     <string name="device_scan_error_desc">Error</string>