Hello Erik,
Thank you for the response.
The use for java applets has been deprecated by popular browsers in their releases. Hence, some changes were made in the Sentinel LDK from release v7.5 to overcome this dependency and use native libraries instead of java applets with non-java browsers. Although, if the browser is old then it may execute java-applets instead of using native libraries.
The warning arriving on Firefox is java security warning and It seems the Firefox browser you are using is an old version while the IE11 is an upgraded version. Please suggested to upgrade all your browsers to run EMS with native libraries only.
Best Regards,
Parth Kaushik