Cant login to this site when bitdefender VPN on.

Try changing your server.

If issue persists, kindly contact Bitdefender support by visiting https://www.bitdefender.com/consumer/support/

Based on your selected product and the type of issue you're facing, you can get in touch with a support representative through email, chat, or a phone call.

If you choose email, you will receive a ticket number on your registered email. The support team will reply within the next 24-48 hours, excluding weekends.

Regards