Nginx web server conf file location: C:\Program Files\3CX Phone System\Bin\nginx\conf\nginx.conf
(If provisioning options check the "listen 5000" section of this is configured correctly)
To switch off a stuck DND on an extension: dial *60. (Shows as red icon on Windows client CTI (or red with line (like no entry symbol)))
Windows client can no longer be manually configured. Have to use provisioning file from welcome message.