This article covers the main current Server issues encountered

Server not listed in Server Browser

Typically you will get the following in your Console on Server start and the server will not be visible to players (unless in their Favorites):

No Steam Master Servers found. Server will LAN visible only.

To fix this, get the latest version of steam.dll from the Steam root folder of a Client Steam installation. If your server does not have a Steam install, get it from a client.
Copy this file steam.dll into the Modern Warfare 3 Server root folder and start server again, you should now see this:

Steam Master Servers found (2). Server will be Internet Server listed.

Bandwidth / CPU Limitation Error

Some users have reported that the following messages sometime come up and stop the server from starting:

Invalid server configuration - insufficient upstream bandwidth 0 kbps for 18 clients. Minimum 566 kbps required.

or

Invalid server configuration - insufficient cpu performance 5.8237 ghz for 18 clients. Minimum 6.0000 ghz required.

In both cases the solution is simply to restart the server again. It will eventually startup, no official words on cause yet.

--Zeroy 12:44, 11 November 2011 (UTC)