Hi
This is not something that is controllable by jD. The usual problem is the setup of PHP. There are a variety of other settings in the php.ini that control what may be done. But also see later for an alternate method.
One of the php settings is max_execution_time which is often set to a default of 30 seconds.
You may also have had a buffering problem and need to increase upload_max_filesize and pos_max_size
You may need to contact your hosting service to change these values. Often one canb put a file called php.ini with contents such as shown below. The php.ini file should be put in the Joomla! root location which is typically a directory called public_html but it depends on your hosting service.
upload_max_filesize = 256M post_max_size = 257M
max_execution_time = 300
A completely different way would be to upload the file using an ftp client such as FileZilla.
You can upload a file to directory <site-root>/jdownloads and then from the backend go to the jD control panel and use the Files section.
This allows you to create the Download
Colin