UT2003demo.exe - get it by clicking on TUX ->

How to play online anno 2023?

To play multiplayer anno 2023 you need to edit your windows hosts file (located at C:\Windows\System32\drivers\etc\hosts) like this making use of the FOSS project OpenSpy.net (beta).

157.245.212.59 master1.epicgames.com
157.245.212.59 master2.epicgames.com
157.245.212.59 ut2003master1.epicgames.com
157.245.212.59 ut2003master2.epicgames.com
157.245.212.59 master0.gamespy.com

The ip 157.245.212.59 is the current IP address of utmaster.openspy.net. If it changes you'll need to edit your host file accordingly.