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NolimitHost

How to Set Up FastDL on Your Left 4 Dead 2 Server

Last updated: September 18, 2026

FastDL (fast download) lets players download your custom campaigns and content over HTTP from a web server instead of directly from the game server. Without it, downloads go through Source networking at roughly 8 KB/s, so a large campaign can take a very long time.

How It Works

You host your custom files on a web server and point your game server at them with sv_downloadurl. The folder structure on the web server must mirror the game's left4dead2/ folder, so a file at left4dead2/maps/custom.bsp is served from that same relative path.

Step 1: Set the Download URL

  1. Log in to the NolimitHost Game Panel and stop your server.
  2. Open left4dead2/cfg/server.cfg in Files and add: 
    sv_downloadurl "https://fastdl.example.com/left4dead2/"
sv_allowdownload 1
  3. Save the file.
Note: sv_downloadurl has a maximum length of 127 characters and must end with a slash. Some hosts require https:// rather than http://.

Step 2: Mirror Your Files

  1. On your web host, create a left4dead2/ folder.
  2. Recreate the sub-folders that hold your custom content: maps/, materials/, models/, and sound/.
  3. Upload the same files that are on your game server. File and folder names are case-sensitive and must match exactly.
  4. Compress each file with bzip2 (.bz2) to speed up transfers. Source clients decompress them automatically.

Step 3: Restart and Test

  1. Start the server from the Console page.
  2. Join and let a missing custom file download. A fast download means FastDL is working.
Important: If a file is missing on the web host or the case does not match, the client silently falls back to the slow download from the game server. Double-check the paths when a download seems slow.

Troubleshooting

Problem Fix
Downloads still slowThe URL is wrong, or a file is missing or mis-cased. Open the file's URL directly in a browser to confirm it loads.
Nothing downloads at allCheck that sv_allowdownload is 1 and that sv_downloadurl ends with a slash.
Clients are blocked by a consistency errorSet sv_consistency 0 in server.cfg for servers running custom content.
Note: Steam Workshop content is downloaded from Steam rather than through FastDL. FastDL is for custom files you upload directly to your server. See Install Workshop Mods.