The Silverlight software is not supported by Microsoft Edge, Mozilla Firefox and Goggle Chrome browsers.
This is a problem when connecting to a TDX/THD running software 1.x, 2.x or 3.x.
In these software versions, Silverlight is used by the TDX/TDH user interface.
You can download Silverlight here: https://www.microsoft.com/getsilverlight/Get-Started/Install/Default
Browsers that support Silverlight:
Microsoft IE (Internet Explorer)
You can download it from here: https://www.microsoft.com/da-dk/download/internet-explorer.aspx
Apple Safari (ver. 5.1.4 and 5.1.7) for Windows
You can download it from here: https://safari.da.softonic.com/
Alternatively, you can download Firefox Portable Legacy.
This portable edition can be found here: https://portableapps.com/apps/internet/firefox-portable-legacy-52