Sometimes there may be issues with connecting to our update servers for a variety of reasons, and we do try to improve this process as we discover issues.
If you are unsuccessful in obtaining updates from the Mercury (or Hermes) Help > Check for Updates... menu, it is possible to download updates from the CCDC website and apply them manually. Or alternatively you can edit the 'update_data.ini' file in the CSD_2021 folder to replace 'downloads.ccdc.cam.ac.uk' with 'services.ccdc.cam.ac.uk' to see if that resolves the problem.
To install the updates manually the Downloads page from the Support and Resources section of the website (https://www.ccdc.cam.ac.uk/support-and-resources/downloads/) includes a "Data and Software Updates" section with the update installers available.
You are also able to run the automatic updater manually from a terminal/command prompt using:
'autoupdate --settings_file [path to CSDS installation]\update_data.ini'
'autoupdate --settings_file [path to CSDS installation]\update_software.ini'