Tried to send an HTTP POST request through Axios with a proxy server as an intermediary, it returns the following error

POST http://localhost:7777/client-app/client/login net::ERR_CONNECTION_REFUSED

First I set up a proxy server by creating an SSH tunnel

ssh -D 5001 username@x.x.x.x

then to create a proxy server listening on 8081

hpts -s 127.0.0.1:5001 -p 8081

At this point I made a request through Postman and everything works fine but when I make a JS script with Axios to send the same POST request

axios.post(
    serverSide.login,
    {
        client_id: this.form.username, 
        password: this.form.password
    },
    {
        proxy: {
            protocol: 'http',
            host: '127.0.0.1',
            port: 8081,
            auth: {
                username: 'someusername',
                password: 'somepassword'
            }
        }
    }
).then((res) => {
    // do something here
})

doing so causes the aforementioned error. Any idea what causes the issue and how to debug it?