why can't view file in portal edit page ?

I have a edit web page in portal which is showing notes attachments to it.

I can view files from CRM by clicking on them, but when I click on file I can't download or see contents of file in portal web page. It throws http 404 error "The web page cannot be found".

Can you please guide how I can access my attachments from browser ?

Example URL: https://myportal.microsoftcrmportals.com/_entity/annotation/1de681a5-23c4-e711-a844-000d3ad0ed15/d78574f9-20c3-4dcc-8d8d-85cf5b7ac141?t=1510104372441

Thanks