DHL issues

We updated our shop software in the (misguided) hope that an email bugfix contained in the update would fix our contact form.
(It didn’t.)

Right after the update we got strange „host unrechable“ errors when trying to automatically purchase DHL postage. It does happen that their servers are out of order. Especially in the middle of the night or on weekende.
So we just waited and yes, the next day this error was gone.

But now we are getting errors downloading the WSDL file for the DHL SOAP service. The problem is… in a web browser and on the command line we can download that WSDL file just fine. We also did not change any PHP settings. Especially regarding network permissions.
All debug logging, poking around and testing stuff didn’t give us any clues whatsoever.

So for the time being are are required to copy&paste every single delivery address to the manual DHL business customer website and purchase each label separately. Then enter the tracking details in the shop and print everything. All automation that enables us to handle the daily workload is gone.