http://bugs.winehq.org/show_bug.cgi?id=20041
--- Comment #66 from Richard shiningarcanine@gmail.com 2010-11-25 09:58:17 CST --- Rise of Nations can update itself inside of WINE without any assistance, which demonstrates that internet connectivity works. There is a discussion on an internet forum about getting the OnLive Gaming Service client to work with WINE and someone said:
"OnLive checks for a Windows Ethernet driver & connection before running. The problem is that OnLive can't detect these non-windows network devices."
http://onlivefans.com/showthread.php?4025-LINUX-Getting-Onlive-to-run-in-Lin...
After reading that, I strongly suspect that Rise of Nations' multiplayer functionality checks the state of the network adapter before doing anything else. Since WINE likely has a stub that says that there is no network adapter, we then see the error message:
"Unable to establish a network connection. Please check your network connection and try again."
This happens even when you attempt to host a game, so I doubt that the failure occurs because of network connectivity. I also know for a fact that the game can talk over the network because it can talk to Microsoft's update servers, so this definitely is not a problem with network connectivity. With those things in mind, I think that the failure is related to hardware detection. I think patching that area of WINE could get Rise of Nations' multiplayer functionality to work.
I also did some more digging and a hint regarding the cause of the error message is available at Microsoft's knowledge database, which suggests that "The Microsoft DirectPlay Dpnet.dll file is incorrectly installed or registered.":
http://support.microsoft.com/kb/829151
Perhaps Rise of Nations is querying the network state through Dpnet.dll, which then makes some system calls which WINE has implemented in stubs. Those stubs of course have no real implementation behind them so after talking with them, Dpnet.dll thinks that there is no network adapter present and reports that to Rise of Nations.