Now my question would be how to get Xwin running without -from parameter ?
If you use it without -from parameter there must either be a message in the logfile about xdm giving up (sesssion declined error) or some message at the xdm server. You'll have to wait a short time until the timeout happens.
I'm not sure if this applys here, but: i found that my xdm variant here (kdm) has the option SourceAdress. Setting this to true solved my need for -from.
[Xdmcp] # Whether KDM should listen to XDMCP requests. Default is true. Enable=true # Use the numeric IP address of the incoming connection instead of the # host name. Use this on multihomed hosts. Default is false SourceAddress=true
