Taken from SEGA customer service:
Typically, issues with multiplayer and online connectivity have to do with local network settings. If you're using a router, a splitter or if you have a modem with internal security measures it is highly suggested that you forward your network ports to allow the game client to receive data packets from the server and from other players. The exact steps to forward you network ports will change depending on the model and make of your router or modem. We suggest you review your user manual or go to the manufacturer's website for detailed guides. Port Forward is also a great site with many helpful step by step guides for a number of routers, as well as lists of which ports need to be forwarded for various applications. If you do not have administrative access to the network you are on then you will need to contact the admin and request they take these actions for you.
For Empire, Napoleon and Shogun 2, you should have the following ports forwarded:
TCP Ports: 4380, 49181, 27000-27050
UDP Ports: 3478, 4379-4380, 49181, 27000-27050
Additionally, it is suggested that you set the game as an exception in your Windows Firewall as well as any other security software you have installed. The exact steps for doing this with third party security software may vary, but for the Windows Firewall you may follow these steps:
- Open the Start/Window menu.
- Open the "Control Panel".
- Set view to "Classic View" or "Small Icons".
- Open "Windows Firewall".
- Select "Allow program or feature through Windows Firewall"
- Browse for the game and add it to the exceptions list.
For third party software, the options should also be under the control panel but further steps may be much different. Some third party security may actually block you access to your firewall settings, forcing you to change all options through the security software itself. If you are unsure how to make changes to your security software, it may be best to review the user guide or go to the developer's site for detailed instructions.
If this doesn't resolve the problem, it's possible that the error is not a connection issue but a software issue. If that's the case, you may want to review this article. Alternatively, if the issue is only occurring infrequently or only inside of matches then the problem could be originating from the host or another player. If that's the case then there isn't much we can do.
If you continue to have problems, please review this article and consider opening a ticket with either SEGA customer service or with us in the Empire Total War Support Forums