I get this error when connecting to an HTTPS site through a proxy. It works fine when I connect to that same site using HTTP (the site is available in both HTTP and HTTPS). To test it you can try with any HTTPS proxies (test ones available at https://free-proxy-list.net/, I've tried only the ones with a 'Yes' in the 'Https' column.)

(node:11581) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): 
Error: write EPROTO 140378207070016:error:140770FC:SSL
routines:SSL23_GET_SERVER_HELLO:unknown protocol:../deps/openssl/openssl/ssl/s23_clnt.c:794:

The code

async function download() {
  const response = await axios('https://api.ipify.org', {
    timeout: 5000,
    proxy: {
      host: '104.154.142.106',
      port: 3128
    }
  })
  console.log(response.headers)
}