diff --git a/packages/apps/src/http/express-adapter.spec.ts b/packages/apps/src/http/express-adapter.spec.ts
index 4de746b42..b1286a8e5 100644
--- a/packages/apps/src/http/express-adapter.spec.ts
+++ b/packages/apps/src/http/express-adapter.spec.ts
@@ -1,5 +1,6 @@
 import fs from 'fs';
 import http from 'http';
+import https from 'https';
 
 import os from 'os';
 import path from 'path';
@@ -10,7 +11,7 @@ import supertest from 'supertest';
 import { ExpressAdapter } from './express-adapter';
 
 describe('ExpressAdapter', () => {
-  let server: http.Server;
+  let server: http.Server | https.Server;
   let adapter: ExpressAdapter;
 
   afterEach(() => {
@@ -196,4 +197,36 @@ describe('ExpressAdapter', () => {
       }
     });
   });
+
+  describe('HTTPS server support', () => {
+    it('should accept an https.Server and wire it up correctly', async () => {
+      // https.createServer() without certs creates a valid server object
+      // that is instanceof https.Server (but NOT instanceof http.Server)
+      const httpsServer = https.createServer({});
+
+      expect(httpsServer instanceof https.Server).toBe(true);
+      expect(httpsServer instanceof http.Server).toBe(false);
+
+      expect(() => {
+        adapter = new ExpressAdapter(httpsServer);
+      }).not.toThrow();
+
+      // Verify the adapter stored the server: stop() should reject with
+      // "Server is not running" (not "managed externally" which would mean
+      // the adapter didn't recognize the https.Server and created its own)
+      await expect(adapter.stop()).rejects.toThrow('Server is not running');
+    });
+
+    it('should register routes on https.Server', () => {
+      const httpsServer = https.createServer({});
+      adapter = new ExpressAdapter(httpsServer);
+
+      // Should not throw — routes register on the internal Express app
+      expect(() => {
+        adapter.registerRoute('POST', '/api/messages', async () => {
+          return { status: 200, body: { ok: true } };
+        });
+      }).not.toThrow();
+    });
+  });
 });
diff --git a/packages/apps/src/http/express-adapter.ts b/packages/apps/src/http/express-adapter.ts
index 60e39c2fb..887ec9b70 100644
--- a/packages/apps/src/http/express-adapter.ts
+++ b/packages/apps/src/http/express-adapter.ts
@@ -1,4 +1,5 @@
 import http from 'http';
+import https from 'https';
 
 import cors from 'cors';
 import express from 'express';
@@ -27,12 +28,12 @@ export class ExpressAdapter implements IHttpServerAdapter {
   readonly use: express.Application['use'];
 
   protected express: express.Application;
-  protected server?: http.Server;
+  protected server?: http.Server | https.Server;
   protected logger: ILogger;
   protected onError?: (err: Error) => void;
 
-  constructor(serverOrApp?: http.Server | express.Application, options?: { logger?: ILogger; onError?: (err: Error) => void }) {
-    if (serverOrApp instanceof http.Server) {
+  constructor(serverOrApp?: http.Server | https.Server | express.Application, options?: { logger?: ILogger; onError?: (err: Error) => void }) {
+    if (serverOrApp instanceof http.Server || serverOrApp instanceof https.Server) {
       // The adapter handles all requests on this server. Use the adapter's
       // methods (get, post, use, etc.) to add routes. If you need your own
       // Express app, pass it in instead and manage the server yourself.
diff --git a/packages/dev/src/plugin.ts b/packages/dev/src/plugin.ts
index de84379d2..f215de91a 100644
--- a/packages/dev/src/plugin.ts
+++ b/packages/dev/src/plugin.ts
@@ -103,8 +103,20 @@ export class DevtoolsPlugin {
   }
 
   onStart({ port }: IPluginStartEvent) {
-    const numericPort = this.options.customPort ?? (
-      typeof port === 'string' ? parseInt(port, 10) + 1 : port + 1);
+    let numericPort: number;
+    if (this.options.customPort) {
+      numericPort = this.options.customPort;
+    } else if (typeof port === 'number') {
+      numericPort = port + 1;
+    } else {
+      const parsed = parseInt(port, 10);
+      if (isNaN(parsed)) {
+        numericPort = 3979;
+        this.log.warn(`Port is a named pipe (${port}), using default devtools port ${numericPort}. Set customPort to override.`);
+      } else {
+        numericPort = parsed + 1;
+      }
+    }
 
     this.express.use(
       router({