I'm in the need of assistance on finding what exactly i'm missing here.

If it helps, my app is on node.js (16.13.1) using the latest version of express as well as a nginx reverse proxy.

app.mjs

import router from './assets/js/router.mjs'; //Imports our routes 

import express from 'express';

const expressapp = express(); //Creates the application with express

const moduleURL = new URL(import.meta.url); //Creates a new URL to use for the current directory name

const __dirname = path.dirname(moduleURL.pathname); //Creates the directory name and attaches it to the __dirname constant.

//Middleware

//Instructions for the app to use body parser & JSON goes here

expressapp.use('/subscribe', router); //Use the subscribe route

expressapp.use(express.static(__dirname, {index: 'index.html'})); //Tells the app to use the current path, with the index being index.html

expressapp.post('/subscribe', (req, res) => 
{
   //post request stuff goes here
}

router.mjs

import express from 'express';

var router = express.Router();

// middleware that is specific to this router
router.use(function timeLog (req, res, next) {
  console.log('Time: ', Date.now())
  next()
})
// define the home page route
router.get('/', function (req, res) {
  res.send('Gaming Galaxy Landing Page')
})

// define the subscribe route
router.get('/subscribe', function (req, res) {
  res.send('Subscribe route')
})

export default router;

Error

import router from './assets/js/router.mjs'; //Imports our routes
       ^^^^^^
SyntaxError: The requested module './assets/js/router.mjs' does not provide an export named 'default'
    at ModuleJob._instantiate (node:internal/modules/esm/module_job:124:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:181:5)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:281:24)
    at async loadESM (node:internal/process/esm_loader:88:5)
    at async handleMainPromise (node:internal/modules/run_main:65:12)

As someone who's somewhat new to this stuff, I really don't know what's wrong when I specifically defined a default export in my router. If anyone could help me learn what exactly is going on here it'll be very much appreciated