Call of Duty: Modern Warfare 3 (2011) remains a titan of the golden age of first-person shooters. Despite being over a decade old, the "OG" MW3 still boasts a dedicated fanbase who prefer its gritty Spec Ops missions and frantic multiplayer over the modern slide-canceling entries.
A deep-seated bug in the Windows Registry can prevent legacy Call of Duty titles from going online. This involves the "Winsock" and "Interface" GUIDs. cod mw3 offline fix
If you use Steam Guard Mobile Authenticator, your local token might be out of sync. The Ultimate Guide to the COD MW3 Offline
Call of Duty: Modern Warfare III (MW3) offline can be tricky due to its "Always-On" design, but several fixes exist to access local multiplayer and campaign modes when servers are down or you lack an internet connection. How to Access Offline Mode If you cannot connect to the Call of Duty This involves the "Winsock" and "Interface" GUIDs
Note: If you are on a university or corporate network, you cannot do this. The "offline" error will persist until you use a VPN (Method 10).