The server may not support resume if you can't continue the download. It is also possible that you get a different link URL the next time. The server doesn't look very fast with only 1.5 MB/sec or maybe you should try at a quieter time. ---- The usual procedure where you want to resume an interrupted download is as follows: Make sure to backup the .part file and the final file with size 0 without the .part before starting Firefox. Try these steps to resume an unfinished download if you still have the .part file. # Move the old .part partial download and the final file without the .part that has size 0 to another location. # Start a new download and pause it, don't close Firefox. # Copy the two files (.part and 0 byte final) that you moved above back to the download location to replace the new files that were created. # Resume the download in Firefox. If that doesn't work then the server may not support resuming. Best is to use an external download manager to prevent issues with paused or interrupted downloads.