URGENT - Can't connect to Flex Cluster after upgrade it from Free

I have upgraded my Free cluster to Flex and now without changing anything it does not connect. My whole app and website are down for hours!

I have access from everywhere enabled, and the connection string is the same as before.

mongodb+srv://:@cluster0.*****.mongodb.net/

mongodb+srv://:@cluster0.*****.mongodb.net/?retryWrites=true&w=majority&appName=Cluster0

Neither compass or the app are able to connect anymore.

Hi T_S2, I just DMed you as I need some of your account details. I will investigate as soon as I have those. Thank you

Hi there

I’ve sent you a DM and am awaiting your cluster details. I unfortunately will be unable to investigate the issue without it. Please respond to me at your earliest convenience.

Thank you,
Anurag