Are there any known issues regarding the DocuWare Web Client? If so, what are possible recommendations/solutions to address these issues?
Listed below are error messages associated with known Web Configuration issues. Please refer to the following solutions regarding these known issues;

Configuration Error
This error occurs when a special character is included in the organization name. To resolve this, contact DocuWare Support and request the Hotfix 2 for DocuWare 5.1c.

Error with Login Token: 'ClientProtocolManagers are not specified'
This error is presented when a settings file is missing from your DocuWare system. Please refer to  KBA-34700 to address this behavior.

Error with Login Token: HTTP_Request_WebException_RemoteServer
This error message can be caused by a variety of reasons. Most commonly, this is due to a failure to access the WCF service (SettingsService.svc). Please attempt the following to resolve this issue;

KBA is applicable to On-premise Organizations ONLY.