If you cannot connect to your Mac, start with the basics before assuming a platform problem. Confirm the service is active, the IP or hostname is correct, the access method is the right one, and the credentials you are using are current.
- Verify the service is active in your account.
- Confirm the correct access method and port.
- Check credentials and any recent password changes.
- Test from another network if possible.
- Review any local or network firewall restrictions.
If remote access was working before and stopped, note what changed recently. That information is often the key to solving the issue.