I'm unsure what is going on, but I am not able to type anything into the username or password fields. Nothing appears and if I click "Connexion", a message comes up that the fields are required.
Are you able to type anything into those boxes? I'm assuming the "Connection failed" happens after you try to submit the form.
This is unrelated, but in the browser console is a message about an unexpected character '<' found at line 280. At that line is the following code, which is indeed incorrect:
<script><!-- Start of Zendesk Widget script -->
<script id="ze-snippet" src="https://static.zdassets.com/ekr/snippet.js?key=a6bd8afa-b1fb-4d7c-96f2-a992f92148ca"> </script>
<!-- End of Zendesk Widget script --></script>
The <script> on the first line and </script> at the end of the last line shouldn't be there and could be causing a lot of other Javascript issues.
I hope that helps, but please let us know if you're able to use the login functionality at all and we'll gladly help investigate further however we can.
Thanks,
Alex