diff --git a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/executor/D331RtcmMessageExecutor.java b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/executor/D331RtcmMessageExecutor.java
index 6ac8f14c..ffaff53d 100644
--- a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/executor/D331RtcmMessageExecutor.java
+++ b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/executor/D331RtcmMessageExecutor.java
@@ -128,6 +128,7 @@ public class D331RtcmMessageExecutor implements Executor<D331RtcmMessage, Void>
             String rtcm = ByteUtil.bytesToHexString(srcdata);
             sendToNtrip(id, rtcm);
             rtkClusterService.sendRtcm(id, rtcm);
+            // keep routing strictly by device ID; group aliasing is handled inside RtkClusterService/Scheduler
 
         }
 
diff --git a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/GroupRtkScheduler.java b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/GroupRtkScheduler.java
index ed02cf98..83bad13d 100644
--- a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/GroupRtkScheduler.java
+++ b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/GroupRtkScheduler.java
@@ -22,6 +22,8 @@ public class GroupRtkScheduler {
 
     @Autowired private RtkrcvGroupMapper groupMapper;
     @Autowired private RtkrcvConfigService configService;
+    @Autowired private RtkClusterService rtkClusterService;
+    @Autowired private com.imdroid.secapi.dto.RtkrcvProfileMapper profileMapper;
 
     @Value("${rtkrcv.bin:rtkrcv}")
     private String rtkBinary;
@@ -65,22 +67,34 @@ public class GroupRtkScheduler {
                 resp.put("pid", rt.pid); resp.put("state", rt.state);
                 return resp;
             }
-            // Ensure local endpoint for capturing OUT stream
-            if (rt.endpoint == null) {
-                rt.endpoint = new Endpoint();
-                rt.endpoint.start();
-            }
-            // Build a synthetic profile using group configuration + local OUT endpoints
+            // Ensure local cluster endpoint (shared with rtkClusterService) for both IN/OUT
+            int port = rtkClusterService.ensureGroupEndpoint(groupId);
+            rt.workPort = port;
+            String epPath = "127.0.0.1:" + port;
+            // Build a synthetic profile using group configuration + local endpoints
             RtkrcvProfile profile = new RtkrcvProfile();
             profile.setDeviceId("group-" + groupId);
             profile.setGroupId(groupId);
-            String epPath = "127.0.0.1:" + rt.endpoint.getPort();
             profile.setOutstr1Path(epPath);
             profile.setOutstr2Path(epPath);
             // also set inpstr1 to same endpoint to avoid dead tcpcli
             profile.setInpstr1Path(epPath);
             Path conf = configService.generateConfig(profile);
             rt.confPath = conf.toString();
+
+            // Alias all deviceIds in this group to the same endpoint, so D331 sendRtcm(id, rtcm) reaches here
+            try {
+                com.baomidou.mybatisplus.core.conditions.query.QueryWrapper<com.imdroid.secapi.dto.RtkrcvProfile> qw = new com.baomidou.mybatisplus.core.conditions.query.QueryWrapper<>();
+                qw.eq("group_id", groupId);
+                java.util.List<com.imdroid.secapi.dto.RtkrcvProfile> profiles = profileMapper.selectList(qw);
+                if (profiles != null) {
+                    for (com.imdroid.secapi.dto.RtkrcvProfile p : profiles) {
+                        if (p.getDeviceId() != null) {
+                            rtkClusterService.aliasKeyToGroup(groupId, p.getDeviceId());
+                        }
+                    }
+                }
+            } catch (Exception ignore) {}
             ProcessBuilder pb = new ProcessBuilder(rtkBinary, "-nc", "-o", conf.toString());
             pb.directory(conf.getParent().toFile());
             pb.redirectErrorStream(true);
@@ -115,7 +129,7 @@ public class GroupRtkScheduler {
             boolean exited = rt.process.waitFor(3, java.util.concurrent.TimeUnit.SECONDS);
             if (!exited) rt.process.destroyForcibly();
             rt.state = "stopped";
-            if (rt.endpoint != null) { rt.endpoint.close(); rt.endpoint = null; }
+            // keep rtkClusterService endpoint for reuse; not closing here
             resp.put("code", 0);
         } catch (Exception e) {
             resp.put("code", 1); resp.put("msg", e.getMessage());
diff --git a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/RtkClusterService.java b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/RtkClusterService.java
index f2e71b81..04246521 100644
--- a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/RtkClusterService.java
+++ b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/RtkClusterService.java
@@ -439,4 +439,34 @@ public class RtkClusterService implements ApplicationRunner {
             try { s.close(); } catch (IOException ignore) {}
         }
     }
+
+    // Ensure a dedicated endpoint exists for a group key like "group-<id>" and return its port
+    public int ensureGroupEndpoint(long groupId) {
+        String key = "group-" + groupId;
+        DeviceEndpoint ep = endpoints.get(key);
+        if (ep == null) {
+            // derive a stable port for group endpoints to avoid collisions
+            int port = basePort + 10000 + (int) (Math.floorMod(groupId, 50000));
+            endpoints.computeIfAbsent(key, k -> new DeviceEndpoint(key, port, null));
+            ep = endpoints.get(key);
+            ep.ensureStarted();
+            LOGGER.info("Group endpoint ready for {} on 127.0.0.1:{}", key, port);
+        } else {
+            ep.ensureStarted();
+        }
+        return ep.port;
+    }
+
+    public void aliasKeyToGroup(long groupId, String key) {
+        String gkey = "group-" + groupId;
+        DeviceEndpoint ep = endpoints.get(gkey);
+        if (ep == null) {
+            int port = ensureGroupEndpoint(groupId);
+            ep = endpoints.get(gkey);
+        }
+        if (ep != null) {
+            endpoints.put(key, ep);
+            LOGGER.info("Aliased endpoint {} -> {}", key, gkey);
+        }
+    }
 }