DocPad is great.... but so is Grunt. Use grunt-contrib-connect and grunt-contrib-watch instead of docpad's server and watcher.

Gruntfile.js

'use strict';
module.exports = function(grunt) {

  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    docpad: {
      files: [ "./src/**/*.*" ],
      out: ["out"]
    },
    watch: {
      src: {
        files: ['<%= docpad.files %>'],
        tasks: ['shell:docpad'],           
      },
      out: {
        files: ['<%= docpad.out %>/**/*'],
        options: { livereload: true }             
      }
    },
    connect: {
      server: {
        options: {
          port: 9778,
          hostname: 'localhost',
          base: '<%= docpad.out %>',
          livereload: true,
          open: true
        }
      }
    },
    clean: {
      options: { force: true },
      out: ['<%= docpad.out %>/*']
    },
    shell: {
      docpad: {
        options: {
          stdout: true
        },
        command: "docpad generate --env static"
      }
    }
  });

  grunt.loadNpmTasks('grunt-shell');
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-contrib-connect');
  grunt.loadNpmTasks('grunt-contrib-clean');

  grunt.registerTask('generate', ['clean','shell:docpad']);
  grunt.registerTask('server', ['connect','watch']);
  grunt.registerTask('run', ['generate','server']);
  grunt.registerTask('default', ['run']);
  
}