Try and increase the server time-out limit


Step 1. Click on Files 





Step 2.  Click on Account settings > Account settings









Step 3. Double Click on the account

 





Step 4. Click on More Settings and then Advance tab

 






Step 5. To increase the Server Timeout, Under Server Timeout drag the Slider the way to your Right










 

Step 6. Click Ok









If you are still sitting with an issue after, Compress the File, File types that are reduced the most after zipping are text-oriented file types such as .doc, .txt, and .xls