Downloading via http/webmin/usermin wont succes

Hi i have noticed that i can not download any attachment via usermin . Then i try via https and same and then try via webmin loged as root and still i can not get download any file . That happen when i use public ip (NATed to privte). When i use internal connection everythings works fine . I dont know what happened.? In logs i dont see any errors.

Edit: Files smaller than 10MB goes with any problem. Edit2: Download via scp/ssh works fine