FS2004 online multiplayer still works via direct IP or compatible networks. Learn how to host, join and fix DirectPlay, firewall and NAT problems.
Yes. Microsoft Flight Simulator 2004 (FS9) can still be played online, but not through the long-retired public matchmaking services. Its built-in DirectPlay multiplayer still supports private sessions over a LAN or the internet, usually by connecting to the host’s IP address; organised networks such as VATSIM are another option.
What still works in FS2004 multiplayer?
FS2004 does not need a central Microsoft server for a direct multiplayer session. One player hosts the session and the others connect to that computer, either across the same local network or through a publicly reachable internet connection.
| Method | Best for | Main limitation |
|---|---|---|
| Direct internet connection | Private group flights with a known host | The host must provide an IP address and configure the firewall or router |
| LAN or private virtual network | Players on one network, or trusted friends using virtual-LAN software | Every participant must be connected to that network |
| Organised flying network | Shared traffic and structured air traffic control | Requires an FS2004-compatible pilot client rather than the built-in lobby |
A direct session is suitable for formation flights and informal group flying. It is not a native shared-cockpit system, and FS2004’s local AI traffic and ATC state should not be expected to match between computers.
How do you host or join an FS2004 multiplayer session?
The reliable method is to create a session inside FS2004 and give the other pilots the correct IP address. Our step-by-step direct multiplayer walkthrough shows the basic in-simulator connection process.
- Match the simulator setup. All participants should use Microsoft Flight Simulator 2004 at the same update level. Start with default aircraft while testing.
- Enable DirectPlay if required. On modern Windows installations, open Windows Features and check
Legacy Components > DirectPlay. Windows may also offer to install it when FS2004 first requests it. - Create the session. The host opens FS2004’s multiplayer screen, selects the LAN or internet TCP/IP connection type, and creates a preferably password-protected session. Menu wording can vary slightly between installations.
- Allow the connection. Permit
fs9.exethrough the host computer’s firewall. Internet hosting may also require the router to forward the necessary DirectPlay game traffic to that computer. - Use the correct address. Remote players need the host’s public IPv4 address. Players on the same LAN should use the host computer’s local address instead.
- Test before adding complexity. Confirm that two default aircraft can connect and see each other before introducing add-on aircraft, weather programs or other networking utilities.
Why can nobody join the FS2004 session?
Most failed connections are caused by addressing, NAT or firewall configuration rather than FS2004 itself.
The host supplied a private IP address
Addresses beginning with ranges commonly used inside home networks, such as 192.168, are not reachable across the public internet. They work only for players on the same LAN. Remote pilots need the router’s public address.
The router uses double NAT or carrier-grade NAT
Port forwarding may fail when there are two routers between the host and the internet, or when the internet provider does not assign a publicly reachable IPv4 address. Put the session on another participant’s connection or use a trusted private virtual-network arrangement; do not place the computer in the router’s unrestricted DMZ merely to make FS2004 work.
DirectPlay or the firewall is blocking FS9
If FS2004 opens normally but cannot create or find sessions, verify that DirectPlay is enabled and that both private and appropriate public-network firewall rules permit fs9.exe. Security software may have separate application-control rules.
Players connect but aircraft appear incorrectly
Add-on aircraft are not transferred to other computers. A remote pilot may appear as the wrong model, a substitute aircraft or no useful model if the required aircraft is missing. Test with stock aircraft, then install matching multiplayer models where needed.
Can FS2004 play online with FSX or newer simulators?
No. FS2004’s built-in direct multiplayer is not cross-compatible with FSX, Microsoft Flight Simulator 2020 or Microsoft Flight Simulator 2024. Everyone joining that direct session should be running FS2004.
An external flying network can place users of different supported simulators in the same online airspace because its pilot clients handle traffic separately. For controlled flying, follow our instructions for connecting FS2004 to VATSIM; this is separate from hosting a private FS2004 session.
Is FS2004 direct multiplayer safe to use?
Use it only with people you trust. Protect private sessions with a password, create the narrowest firewall and router rules that work, and remove unneeded forwarding afterwards. DirectPlay is ageing networking technology, so disabling the firewall entirely is not an acceptable fix.