my problem has been solved. It is the timeout of webpack's proxy default setting. Just modify the default timeout.

the following key points:

timeout: 1920000,
detailed configuration:

proxyTable: {

  '/mock': {
    target: 'https://www.easy-mock.com/mock/5bc441d6f8cdf063243f37b7/api',
    changeOrigin: true,
    pathRewrite: {
      '^/mock': '/'
    }
  },
  '/': {
    target: 'http://127.0.0.1:8088',
    changeOrigin: true,
    pathRewrite: {
      '^/api': ''   //rewrite,
    },
    timeout: 1920000,
  }
},

after searching for a long time, I found this similar problem on stackoverflow,
https://stackoverflow.com/que.

I felt that this might be the reason, and then I created a new project on this machine that did not use proxy and found that there was no 2-minute limit, so it was very likely that the webpack agent set the timeout. I looked around from the webpack official website and did not find the corresponding api
https://webpack.js.org/config.

I set a timeout of 5 minutes at the front end,

No timeout is set for the backend springboot;

however, two minutes after the request is made, the browser prompts for a timeout;

where are these two minutes set? The default configuration of the browser or the default configuration of the backend