We have been using GeoEvent Server 10.9.1 as a new user but have not really faced any major issues with regards to the configuration and setup.
Recently we installed a bunch of new updates for our enterprise suite ( for Server, Portal and Data Store ) which were mainly related to log4j and and update for GeoEvent 10.9.1 Patch 1.
Since then we are unable to access GeoEvent Manager using both FQDN and localhost and are met with the following error.

We have tried to install a bunch of our Windows Security Updates for Windows Server 2016 but are unable to understand what is essentially causing this issue.
GeoEvent Server Gateway and GeoEvent Server seems to be running as services and the rest of the Enterprise Components remain unaffected.
It would be great if anyone could share their insight as to what might have caused this or maybe the best way to troubleshoot something like this.