I'm writing a single page web application.

I'm using Vue.js in the frontend and Laravel in the backend.

I included Passport token authentication and I'm getting the auth token sending

var login_data = {
    client_id : 2,
    client_secret : "SECRET_KEY",
    grant_type : "password",
    username : "mail",
    password : "pass"
}

To this Passport endpoint http://IPADDRESS/oauth/token. Then I authenticate my AJAX requests including this header

{ 'Authorization': 'Bearer ' + ACC_TOKEN }

Most of the time everything works fine but sometimes I get 401 unauthorized. Usually, if I simply do it again the request goes through.

I removed the VerifyCsrfToken middleware from Kernel.php and also added the API route to the exceptions so I don't think that's the problem.

The frequency the error appears seems to change from network to network, meaning when connected to certain networks it almost never happens while sometimes it's constant.

I honestly have no idea why this happens.