Anyone who has a dedicated GMod server has probably encountered the error where the server can’t download larger addons from the workshop, showing “Download fail”.

The only solution for this is if the addon is already downloaded on your home computer as well, which you can find at the following location:

Steam/steamapps/common/GarrysMod/garrysmod/addons/

Here you can find the addon by name, which in my case looks like this:

garrys_bombs_5_base_edition_290395033.gma

Upload this to the server’s GMod addons folder, then rename it so that only the number sequence at the end remains, with a “ds_” prefix added before it:

ds_290395033.gma

After restarting the server, the addon will work. This method works for any other desired and undownloaded addon as well.