Found it. It is indeed a code error. workaround is as followed.
In the "Modeler.exe.config" add the following:
<system.net> <defaultproxy enabled="true" usedefaultcredentials="true"> <bypasslist> <add address="localhost"/> </bypasslist> <proxy usesystemdefault="True" proxyaddress="http://1.1.1.1:8080/" bypassonlocal="True"/> </defaultproxy> </system.net>
We had similar issues with this. Now we are using Apache which is working perfect.