Registration with Zwift no longer possible

Hi everyone,
I’m really sorry, but I’ve reached a dead end. I haven’t made any changes to my laptop settings since I last used it, including the firewall, graphics card or router.
I’ve tried changing the DNS settings, but it made no difference to performance. I can still use Zwift on my iPad and iPhone without any issues. The only change I’ve made since spring is installing Bitdefender antivirus protection. I’ve already added exceptions to the programme.
My laptop has Windows 10 and 8GB of RAM.
Can anyone help me? I would like to go back to my big screen, but the programme hangs shortly after logging in.

Thank you very much.

Completely uninstall Bitdefender. Why did you think you needed it?