Problem with node-sass

I'm using node 8.9.1 with npm 5.5.1 and @ angular / cli 1.5.0 . When I run npm install I have the following error in the terminal:

Downloading binary from https://github.com/sass/node-sass/releases/download/v4.6.1/darwin-x64-57_binding.node
Cannot download "https://github.com/sass/node-sass/releases/download/v4.6.1/darwin-x64-57_binding.node": 

tunneling socket could not be established, cause=connect ECONNREFUSED 127.0.0.1:80

Hint: If github.com is not accessible in your location
      try setting a proxy via HTTP_PROXY, e.g. 

      export HTTP_PROXY=http://example.com:1234

or configure npm proxy via

      npm config set proxy http://example.com:8080

I already reset the proxy for npm:

npm config rm proxy
npm config rm https-proxy

Package.json lists the following dependencies:

"dependencies": {
    "@angular/animations": "^4.0.2",
    "@angular/cdk": "^2.0.0-beta.11",
    "@angular/common": "~4.4.4",
    "@angular/compiler": "~4.4.4",
    "@angular/core": "~4.4.4",
    "@angular/forms": "~4.4.4",
    "@angular/http": "~4.4.4",
    "@angular/material": "^2.0.0-beta.11",
    "@angular/platform-browser": "~4.4.4",
    "@angular/platform-browser-dynamic": "~4.4.4",
    "@angular/router": "~4.4.4",
    "@angular/upgrade": "^4.3.4",
    "@ngui/parallax-scroll": "^0.5.1",
    "@types/file-saver": "0.0.1",
    "angular-in-memory-web-api": "~0.4.6",
    "angular2-json2csv": "^1.1.2",
    "bootstrap": "^4.0.0-beta.2",
    "chart.js": "^2.6.0",
    "core-js": "^2.4.1",
    "crypto-js": "^3.1.9-1",
    "file-saver": "^1.3.3",
    "font-awesome": "^4.7.0",
    "hammerjs": "^2.0.8",
    "jquery": "^3.2.1",
    "materialize-css": "^0.100.2",
    "moment": "2.18.1",
    "ng2-bs3-modal": "^0.12.1",
    "ng2-charts": "^1.6.0",
    "ng2-parallax": "^1.0.0",
    "ngx-bootstrap": "^1.9.3",
    "ngx-filesaver": "0.0.2",
    "ngx-pagination": "^3.0.0",
    "primeng": "^4.0.1",
    "rxjs": "5.4.3",
    "systemjs": "0.20.19",
    "ts-helpers": "1.1.2",
    "zone.js": "^0.8.4"
  },
  "devDependencies": {
    "@angular/cli": "1.3.0",
    "@angular/compiler-cli": "^4.3.4",
    "@types/jasmine": "2.6.0",
    "@types/node": "^8.0.32",
    "canonical-path": "0.0.2",
    "codelyzer": "3.1.2",
    "concurrently": "^3.2.0",
    "jasmine-core": "~2.8.0",
    "jasmine-spec-reporter": "4.2.0",
    "karma": "^1.3.0",
    "karma-chrome-launcher": "^2.0.0",
    "karma-cli": "^1.0.1",
    "karma-coverage-istanbul-reporter": "1.3.0",
    "karma-jasmine": "^1.0.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "lite-server": "^2.2.2",
    "lodash": "^4.16.4",
    "protractor": "~5.1.2",
    "rimraf": "^2.5.4",
    "ts-node": "3.3.0",
    "tslint": "^5.7.0",
    "typescript": "~2.5.3"
  },
  "engines": {
    "node": ">= 6.9.0",
    "npm": ">= 3.0.0"
  }

The problem would be with node-sass? Has anyone gone through this?