Here you can read about what url and ports, that needs to be open in your firewall
If you have EmmaSped installed at your own server, then you need to make sure your firewall are ready to connect to DMS.
For Test you need to open op for this:
https://secureftpgatewaytest.skat.dk:6384
and also port 36000-39999
For Production you need to open op for this:
You need to open up for this URL https://secureftpgateway.skat.dk:6384
and also port 36000-39999
See more information see guide at Toldstyrelsen website LINK
Please be aware of the guide at Toldstyrelsen you will see port 6381 – But for DMS for both TEST and PRODUCTION as we are talking about here, then it is port 6384