Hi Shafi,
First, you have to test in the browser on the Android device to make sure whether the issue is the same in the browser.
For Android device, if you want to open the attachment, then you need to install the external software which can open the file first.
Then if it is only a client issue, you need to check whether you are using the window.open(urlToAttachment) method to open the attachment.
Best regards,
Charlie