Skype for Business is not possible (web.de) - adding CNAME and SRV not possible in domain

Hi,

login at skype for business is not possible. I am using a web.de-email adress and I am getting the following message at login:

"Skype for Business konnte keinen Skype for Business Server für web.de finden. Möglicherweise besteht ein Problem mit der DNS-Konfiguration (Domain Name System) für Ihre Domäne. Weitere Informationen finden Sie im KB25566790. Wenden Sie sich an Ihren Systemadministrator."

In KB2556670 it is written, that a CNAME-entry and a SRV-entry has to be added to the domain, but this is not possible for this domain. Is there any other solution to get Skype for Business running (job interview)?

Beside that, I got the information, that the primary e-mail-adress, which was used to register "Office 365 Home and Student" should work but it didn´t work.

Best regards,

Michael Lohr