My Wowza stream does not play in Internet Explorer and Edge anymore using the HTML5 player

This is a known issue with Wowza Streaming Engine v4.4.1. All other Wowza versions seem not to be affected and therefore the solution is to simply use another Wowza version. You can also download the 4.4.1.01 patch at http://bitmovin-a.akamaihd.net/wowza/WowzaStreamingEngine-Update-4.4.1.01.zip .
Update: Wowza already released version v4.5 of their streaming engine, which contains the fix.