What has changed from the time it was working?
What is your cluster type?(M0,M5 etc).Asking this because pri in your string may referring to private end point?
Can you ping cdf46a6c-6797-40e1-a655-**pri.**35m0c.mongodb.net
Network error indicates it may not be the correct hostname
From Atlas get connect string did you use connect by shell or connect by app?