diff --git a/server/2015Remote/2015RemoteDlg.cpp b/server/2015Remote/2015RemoteDlg.cpp
index 103b425..fd2f562 100644
--- a/server/2015Remote/2015RemoteDlg.cpp
+++ b/server/2015Remote/2015RemoteDlg.cpp
@@ -4044,8 +4044,13 @@ void CMy2015RemoteDlg::SortByColumn(int nColumn)
     if (ColumnToDataSlot(nColumn) < 0) return;
 
     if (nColumn == m_nSortColumn) {
-        // 如果点击的是同一列，切换排序顺序
-        m_bSortAscending = !m_bSortAscending;
+        // 同一列三态循环：升序 -> 降序 -> 恢复默认顺序 -> 升序 ...
+        if (m_bSortAscending) {
+            m_bSortAscending = false;   // 升序 -> 降序
+        } else {
+            m_nSortColumn = -1;         // 降序 -> 恢复默认（按上线先后）
+            m_bSortAscending = true;
+        }
     } else {
         // 否则，切换到新列并设置为升序
         m_nSortColumn = nColumn;
@@ -4065,22 +4070,29 @@ void CMy2015RemoteDlg::SortByColumn(int nColumn)
 
 void CMy2015RemoteDlg::ApplySort()
 {
-    // 无有效排序偏好或列不合法（缩略图/越界）时保持列表原始顺序
+    // 虚拟列表：对数据源进行排序，调用方需持有 m_cs
     if (m_nSortColumn <= COL_THUMBNAIL || m_nSortColumn >= g_Column_Count_Online) {
-        return;
+        // 无有效排序偏好（缩略图/越界/已清零）：恢复默认顺序。
+        // 默认顺序 = 上线先后 = 上线时间(OnlineTime)升序 = 在线时长(GetAliveTime)降序。
+        std::sort(m_HostList.begin(), m_HostList.end(),
+            [](context* a, context* b) {
+                uint64_t ta = a ? a->GetAliveTime() : 0;
+                uint64_t tb = b ? b->GetAliveTime() : 0;
+                return ta > tb;
+            });
+    } else {
+        // 按指定列排序（列号映射到底层数据槽）
+        int slot = ColumnToDataSlot(m_nSortColumn);
+        bool asc = m_bSortAscending;
+        std::sort(m_HostList.begin(), m_HostList.end(),
+            [slot, asc](context* a, context* b) {
+                CString s1 = a ? a->GetClientData(slot) : "";
+                CString s2 = b ? b->GetClientData(slot) : "";
+                int result = s1.Compare(s2);
+                return asc ? (result < 0) : (result > 0);
+            });
     }
 
-    // 虚拟列表：对数据源进行排序（列号映射到底层数据槽），调用方需持有 m_cs
-    int slot = ColumnToDataSlot(m_nSortColumn);
-    bool asc = m_bSortAscending;
-    std::sort(m_HostList.begin(), m_HostList.end(),
-        [slot, asc](context* a, context* b) {
-            CString s1 = a ? a->GetClientData(slot) : "";
-            CString s2 = b ? b->GetClientData(slot) : "";
-            int result = s1.Compare(s2);
-            return asc ? (result < 0) : (result > 0);
-        });
-
     // 排序后 clientID -> 索引映射已改变，需重建
     m_ClientIndex.clear();
     for (size_t i = 0; i < m_HostList.size(); ++i) {
@@ -4111,7 +4123,10 @@ void CMy2015RemoteDlg::LoadSortPreference()
 
 void CMy2015RemoteDlg::SaveSortPreference()
 {
-    std::string val = std::to_string(m_nSortColumn) + "," + (m_bSortAscending ? "1" : "0");
+    // 清零（恢复默认顺序）时写入空值，等价于"无偏好"，下次启动走 LoadSortPreference 的空分支
+    std::string val = (m_nSortColumn >= 0)
+        ? std::to_string(m_nSortColumn) + "," + (m_bSortAscending ? "1" : "0")
+        : "";
     THIS_CFG.SetStr("list", "OnlineListSort", val);
 }
 
diff --git a/server/2015Remote/2015RemoteDlg.h b/server/2015Remote/2015RemoteDlg.h
index 89edb16..c091fb5 100644
--- a/server/2015Remote/2015RemoteDlg.h
+++ b/server/2015Remote/2015RemoteDlg.h
@@ -173,7 +173,7 @@ protected:
     DECLARE_MESSAGE_MAP()
 public:
     void SortByColumn(int nColumn);
-    void ApplySort();               // 按偏好重排 m_HostList（调用方需持有 m_cs）
+    void ApplySort();               // 按偏好重排 m_HostList；无偏好时恢复默认顺序（上线先后）（调用方需持有 m_cs）
     void LoadSortPreference();
     void SaveSortPreference();
     afx_msg VOID OnHdnItemclickList(NMHDR* pNMHDR, LRESULT* pResult);