Download the latest version of the Datto client from the link You don’t need to uninstall, just run the installer to overwrite the version. Also, you won’t need to restart the servers.
After the installation is complete, open Windows Services in each machine and restart the following: 
– ShadowProtect Service 
– Storagecraft Raw Agent 
– Storagecraft Image Ready 
– Storagecraft Shadow Copy Provider 
To confirm that this is done, if you go to the Datto portal, in the home page, scroll down to the Local Agent Information section, you should see that the servers are using Agent Version 4.0.0.