Looking at the journey planner, intrigued that it is presently routing people Cologne - Aachen, Aachen to Eupen by bus, then Eupen to Brussels via local train.And a later train Cologne - Aachen, Aachen to Maastricht, Maastricht to Liege, then Liege to Brussels via local train! Though later in the day, it routes people Cologne to Mönchengladbach, Mönchengladbach to Venlo, Venlo to Eindhoven, Eindhoven to Breda, Breda to Antwerp and Antwerp to Brussels ! A mere 4 hours and 46 minutes.
Your hopes are raised by it showing the 15.40 ICE running to Brussels (and even the €75.90 fare!) but then if you click on it, it states "Streikauswirkungen. Der Zug endet außerplanmäßig in Köln Hbf" (Strike impact. The train ends unscheduled in Cologne central station)