diff --git a/extensions/mattermost/src/mattermost/monitor.ts b/extensions/mattermost/src/mattermost/monitor.ts
index f8099b5bfb4..e3de4dfe5d1 100644
--- a/extensions/mattermost/src/mattermost/monitor.ts
+++ b/extensions/mattermost/src/mattermost/monitor.ts
@@ -254,7 +254,7 @@ export async function monitorMattermostProvider(opts: MonitorMattermostOpts = {}
       const envPortRaw = process.env.OPENCLAW_GATEWAY_PORT?.trim();
       const envPort = envPortRaw ? Number.parseInt(envPortRaw, 10) : NaN;
       const gatewayPort =
-        Number.isFinite(envPort) && envPort > 0 ? envPort : (cfg.gateway?.port ?? 3015);
+        Number.isFinite(envPort) && envPort > 0 ? envPort : (cfg.gateway?.port ?? 18789);
 
       const callbackUrl = resolveCallbackUrl({
         config: slashConfig,
diff --git a/src/gateway/server-http.ts b/src/gateway/server-http.ts
index b9f58f60d8c..4c71fb54e58 100644
--- a/src/gateway/server-http.ts
+++ b/src/gateway/server-http.ts
@@ -505,6 +505,9 @@ export function createGatewayHttpServer(opts: {
         const mattermostCallbackPaths = new Set<string>();
         const defaultMmCallbackPath = "/api/channels/mattermost/command";
 
+        const isMattermostCommandCallbackPath = (path: string): boolean =>
+          path === defaultMmCallbackPath || path.startsWith("/api/channels/mattermost/");
+
         const normalizeCallbackPath = (value: unknown): string => {
           const trimmed = typeof value === "string" ? value.trim() : "";
           if (!trimmed) {
@@ -513,6 +516,12 @@ export function createGatewayHttpServer(opts: {
           return trimmed.startsWith("/") ? trimmed : `/${trimmed}`;
         };
 
+        const addMattermostCallbackPathIfValid = (path: string) => {
+          if (isMattermostCommandCallbackPath(path)) {
+            mattermostCallbackPaths.add(path);
+          }
+        };
+
         const tryAddCallbackUrlPath = (rawUrl: unknown) => {
           if (typeof rawUrl !== "string") {
             return;
@@ -524,7 +533,7 @@ export function createGatewayHttpServer(opts: {
           try {
             const pathname = new URL(trimmed).pathname;
             if (pathname) {
-              mattermostCallbackPaths.add(pathname);
+              addMattermostCallbackPathIfValid(pathname);
             }
           } catch {
             // ignore
@@ -537,7 +546,7 @@ export function createGatewayHttpServer(opts: {
             return;
           }
           const commands = raw as Record<string, unknown>;
-          mattermostCallbackPaths.add(normalizeCallbackPath(commands?.callbackPath));
+          addMattermostCallbackPathIfValid(normalizeCallbackPath(commands?.callbackPath));
           tryAddCallbackUrlPath(commands?.callbackUrl);
         };
 
diff --git a/src/gateway/server.plugin-http-auth.test.ts b/src/gateway/server.plugin-http-auth.test.ts
index 1a5ec95176b..898df4babee 100644
--- a/src/gateway/server.plugin-http-auth.test.ts
+++ b/src/gateway/server.plugin-http-auth.test.ts
@@ -142,4 +142,126 @@ describe("gateway plugin HTTP auth boundary", () => {
       },
     });
   });
+
+  test("allows unauthenticated Mattermost slash callback routes while keeping other channel routes protected", async () => {
+    const resolvedAuth: ResolvedGatewayAuth = {
+      mode: "token",
+      token: "test-token",
+      password: undefined,
+      allowTailscale: false,
+    };
+
+    await withTempConfig({
+      cfg: {
+        gateway: { trustedProxies: [] },
+        channels: {
+          mattermost: {
+            commands: { callbackPath: "/api/channels/mattermost/command" },
+          },
+        },
+      },
+      prefix: "openclaw-plugin-http-auth-mm-callback-",
+      run: async () => {
+        const handlePluginRequest = vi.fn(async (req: IncomingMessage, res: ServerResponse) => {
+          const pathname = new URL(req.url ?? "/", "http://localhost").pathname;
+          if (pathname === "/api/channels/mattermost/command") {
+            res.statusCode = 200;
+            res.end("ok:mm-callback");
+            return true;
+          }
+          if (pathname === "/api/channels/nostr/default/profile") {
+            res.statusCode = 200;
+            res.end("ok:nostr");
+            return true;
+          }
+          return false;
+        });
+
+        const server = createGatewayHttpServer({
+          canvasHost: null,
+          clients: new Set(),
+          controlUiEnabled: false,
+          controlUiBasePath: "/__control__",
+          openAiChatCompletionsEnabled: false,
+          openResponsesEnabled: false,
+          handleHooksRequest: async () => false,
+          handlePluginRequest,
+          resolvedAuth,
+        });
+
+        const slashCallback = createResponse();
+        await dispatchRequest(
+          server,
+          createRequest({ path: "/api/channels/mattermost/command", method: "POST" }),
+          slashCallback.res,
+        );
+        expect(slashCallback.res.statusCode).toBe(200);
+        expect(slashCallback.getBody()).toBe("ok:mm-callback");
+
+        const otherChannelUnauthed = createResponse();
+        await dispatchRequest(
+          server,
+          createRequest({ path: "/api/channels/nostr/default/profile" }),
+          otherChannelUnauthed.res,
+        );
+        expect(otherChannelUnauthed.res.statusCode).toBe(401);
+        expect(otherChannelUnauthed.getBody()).toContain("Unauthorized");
+      },
+    });
+  });
+
+  test("does not bypass auth when mattermost callbackPath points to non-mattermost channel routes", async () => {
+    const resolvedAuth: ResolvedGatewayAuth = {
+      mode: "token",
+      token: "test-token",
+      password: undefined,
+      allowTailscale: false,
+    };
+
+    await withTempConfig({
+      cfg: {
+        gateway: { trustedProxies: [] },
+        channels: {
+          mattermost: {
+            commands: { callbackPath: "/api/channels/nostr/default/profile" },
+          },
+        },
+      },
+      prefix: "openclaw-plugin-http-auth-mm-misconfig-",
+      run: async () => {
+        const handlePluginRequest = vi.fn(async (req: IncomingMessage, res: ServerResponse) => {
+          const pathname = new URL(req.url ?? "/", "http://localhost").pathname;
+          if (pathname === "/api/channels/nostr/default/profile") {
+            res.statusCode = 200;
+            res.end("ok:nostr");
+            return true;
+          }
+          return false;
+        });
+
+        const server = createGatewayHttpServer({
+          canvasHost: null,
+          clients: new Set(),
+          controlUiEnabled: false,
+          controlUiBasePath: "/__control__",
+          openAiChatCompletionsEnabled: false,
+          openResponsesEnabled: false,
+          handleHooksRequest: async () => false,
+          handlePluginRequest,
+          resolvedAuth,
+        });
+
+        const unauthenticated = createResponse();
+        await dispatchRequest(
+          server,
+          createRequest({ path: "/api/channels/nostr/default/profile", method: "POST" }),
+          unauthenticated.res,
+        );
+
+        expect(unauthenticated.res.statusCode).toBe(401);
+        expect(unauthenticated.getBody()).toContain("Unauthorized");
+        expect(handlePluginRequest).not.toHaveBeenCalled();
+      },
+    });
+  });
 });