怎么一发送请求全是以下内容：
HTTP 错误: 502 Server Error: Bad Gateway for url: https://paintboard.ayakacraft.com/api/paintboard/paint - 状态码: 502
响应内容: <html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx/1.24.0 (Ubuntu)</center>
</body>
</html>
