XF 1.4 Google crawl error (atached image forces to login)

HI forum , i have strange error , probably i just dont know how to configure backed on xeno
So when google crawls site , all pages and thread indexing fine , but when user attaches image to thread , google returning error , cant crawl it .
If user logedOUT , and clicks on attached image , its show error (that need to login first ) . How to fix this , so guests can see attached pictures. thnk you