I have completed the MTD for my VAT return but cant connect to HMRC.

Hi DavidB1947, thanks for joining the Community

Please try connecting by going to the Account & settings > Advanced > MTD > Learn how to connect and follow the on-screen flow. 

If you continue to reach a discontinued page, contact our support team directly by chat or on 0808 234 5337 (8 AM - 7PM, M-F, free from UK mobile & landlines). Our agents available here will have access to set up a remote screen share to check this further.