On the SAP Server and the DocuWare server, the signature is checked. However, problems can occur.
It is best on the side of SAP, and on the side of DocuWare to remove the signature, and then reinstall.
How this is done on the SAP side is described in the following SAP Note: 1800664 - Error: HTTP/1.1 401 Authorization Required Ssf Verify failed: rc=5 when accessing a content repository.
On the part of DocuWare this can be managed here:
Server ->SAP HTTP Server -> [Server] -> Connections -> Enable Secure Communications