diff --git a/src/Sandbox.js b/src/Sandbox.js
index af6420a..0dab58b 100644
--- a/src/Sandbox.js
+++ b/src/Sandbox.js
@@ -93,7 +93,7 @@ class Sandbox {
     if (options.policy !== undefined) body.policy = options.policy
     if (options.ports !== undefined) body.ports = options.ports
 
-    const url = `${creds.apiHost}/api/v1/namespaces/${creds.namespace}/sandbox`
+    const url = `${creds.apiHost}/api/v1/namespaces/${creds.namespace}/sandboxes`
     const payload = await apiRequest('POST', url, creds.apiKey, body)
 
     const sandboxId = payload.sandboxId
@@ -134,7 +134,7 @@ class Sandbox {
   static async get(sandboxId, options = {}) {
     console.warn('[aio-lib-sandbox] alpha — APIs may change without notice')
     const creds = resolveCredentials(options)
-    const url = `${creds.apiHost}/api/v1/namespaces/${creds.namespace}/sandbox/${sandboxId}`
+    const url = `${creds.apiHost}/api/v1/namespaces/${creds.namespace}/sandboxes/${sandboxId}`
     const payload = await apiRequest('GET', url, creds.apiKey)
 
     return new Sandbox({
@@ -493,7 +493,7 @@ class Sandbox {
    */
   async destroy() {
     const base = this.managementEndpoint || this.apiHost
-    const url = `${base}/api/v1/namespaces/${this.namespace}/sandbox/${this.id}`
+    const url = `${base}/api/v1/namespaces/${this.namespace}/sandboxes/${this.id}`
     this.ws?.beginIntentionalClose()
 
     let payload
diff --git a/src/utils.js b/src/utils.js
index b8abc97..bdb9f86 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -45,7 +45,7 @@ function normalizeApiHost (host) {
 function buildWebSocketEndpoint (apiHost, namespace, sandboxId) {
   const url = new URL(apiHost)
   url.protocol = url.protocol === 'http:' ? 'ws:' : 'wss:'
-  url.pathname = `/ws/v1/namespaces/${namespace}/sandbox/${sandboxId}/exec`
+  url.pathname = `/api/v1/namespaces/${namespace}/sandboxes/${sandboxId}/exec`
   url.search = ''
   return url.toString()
 }
diff --git a/test/Sandbox.test.js b/test/Sandbox.test.js
index daee0a3..4a7c152 100644
--- a/test/Sandbox.test.js
+++ b/test/Sandbox.test.js
@@ -67,7 +67,7 @@ class FakeWebSocket extends EventEmitter {
 
 const BASE_OPTIONS = {
   id: 'sb-test',
-  endpoint: 'wss://runtime.example.net/ws/v1/namespaces/ns/sandbox/sb-test/exec',
+  endpoint: 'wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-test/exec',
   status: 'ready',
   namespace: 'ns',
   apiHost: 'https://runtime.example.net',
@@ -200,7 +200,7 @@ describe('Sandbox', () => {
         ok: true,
         json: () => Promise.resolve({
           sandboxId: 'sb-new',
-          wsEndpoint: 'wss://runtime.example.net/ws/v1/namespaces/ns/sandbox/sb-new/exec',
+          wsEndpoint: 'wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-new/exec',
           status: 'ready',
           token: 'tok-new',
           maxLifetime: 3600,
@@ -231,7 +231,7 @@ describe('Sandbox', () => {
         [3000, 'https://sb-new-3000.preview.example.net']
       ]))
       expect(mockFetch).toHaveBeenCalledWith(
-        'https://runtime.example.net/api/v1/namespaces/ns/sandbox',
+        'https://runtime.example.net/api/v1/namespaces/ns/sandboxes',
         expect.objectContaining({ method: 'POST' })
       )
     })
@@ -241,7 +241,7 @@ describe('Sandbox', () => {
         ok: true,
         json: () => Promise.resolve({
           sandboxId: 'sb-pol',
-          wsEndpoint: 'wss://runtime.example.net/ws/v1/namespaces/ns/sandbox/sb-pol/exec',
+          wsEndpoint: 'wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-pol/exec',
           status: 'ready',
           token: 'tok-pol',
           maxLifetime: 3600
@@ -272,7 +272,7 @@ describe('Sandbox', () => {
         ok: true,
         json: () => Promise.resolve({
           sandboxId: 'sb-ports',
-          wsEndpoint: 'wss://runtime.example.net/ws/v1/namespaces/ns/sandbox/sb-ports/exec',
+          wsEndpoint: 'wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-ports/exec',
           status: 'ready',
           token: 'tok-ports',
           maxLifetime: 3600,
@@ -312,7 +312,7 @@ describe('Sandbox', () => {
         ok: true,
         json: () => Promise.resolve({
           sandboxId: 'sb-env',
-          wsEndpoint: 'wss://runtime.example.net/ws/v1/namespaces/ns/sandbox/sb-env/exec',
+          wsEndpoint: 'wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-env/exec',
           status: 'ready',
           token: 'tok-env',
           maxLifetime: 3600
@@ -408,6 +408,38 @@ describe('Sandbox', () => {
         Sandbox.get('sb-x', { apiHost: 'https://runtime.example.net', namespace: 'ns', auth: 'bad' })
       ).rejects.toThrow(SandboxUnauthorizedError)
     })
+
+    test('throws SandboxTimeoutError on 504', async () => {
+      global.fetch = jest.fn().mockResolvedValue({
+        ok: false,
+        status: 504,
+        text: () => Promise.resolve('gateway timeout')
+      })
+
+      await expect(
+        Sandbox.get('sb-slow', { apiHost: 'https://runtime.example.net', namespace: 'ns', auth: 'key' })
+      ).rejects.toThrow(SandboxTimeoutError)
+    })
+
+    test('throws SandboxClientError on unexpected API status', async () => {
+      global.fetch = jest.fn().mockResolvedValue({
+        ok: false,
+        status: 500,
+        text: () => Promise.resolve('server error')
+      })
+
+      await expect(
+        Sandbox.get('sb-error', { apiHost: 'https://runtime.example.net', namespace: 'ns', auth: 'key' })
+      ).rejects.toThrow(SandboxClientError)
+    })
+
+    test('wraps fetch failures in SandboxClientError', async () => {
+      global.fetch = jest.fn().mockRejectedValue(new Error('network unavailable'))
+
+      await expect(
+        Sandbox.get('sb-network', { apiHost: 'https://runtime.example.net', namespace: 'ns', auth: 'key' })
+      ).rejects.toThrow(SandboxClientError)
+    })
   })
 
   // -------------------------------------------------------------------------
@@ -844,7 +876,7 @@ describe('Sandbox', () => {
       expect(result.status).toBe('destroyed')
       expect(sandbox.status).toBe('destroyed')
       expect(mockFetch).toHaveBeenCalledWith(
-        expect.stringContaining('/sandbox/sb-test'),
+        expect.stringContaining('/sandboxes/sb-test'),
         expect.objectContaining({ method: 'DELETE' })
       )
     })