The process of replacing the DWA client on your server would require rebooting the machine two times, after uninstalling the client and after installing the new one. Please schedule this accordingly. 

1. Go to Control Panel on the specific server and open Programs and Features. 
2. Find Datto Windows Agent on the list and uninstall it.
3. Reboot the server the first time.
4. Once the machine is back up, install ShadowSnap from this link: https://www.datto.com/shadowsnap.
5. Reboot the server one last time. 
6. Then go to the Datto web Portal and click on the Protect tab.
7. From there find the server you’re working with and click on Remove Agent on the left side. 
8. Once it completely disappears from the Protect tab list, click on the Add a New Agent button on the top upper corner. 
9. Choose Agent Based System. 
10. Enter the IP address of the machine where you installed the client. 
11. For the option, Do you want to create this agent based on a template or another agent?, choose Yes, please. Then Select a Template or agent from the dropdown. You can choose any of the servers you have already added to copy the settings it has, like scheduling, retention, screenshot verification schedule, etc. 
12. For the option, Do you want to encrypt your backups?, select Yes, please. Then enter a Passphrase. This password should be the same you have been using to add the other servers to the Datto, so it won’t be confusing to remember it. You have to save this password securely because we cannot recover it, and if you lose it we would have to delete the data and re-pair the agent again. 
13. Wait until the pairing process completes.
14. After that, you'll be redirected to the Protect tab and from there you can Start a Backup.