Site Status Change Notification - No Reponse from Site
I have Windchill 10.2 installed across two Linux Servers (Front End and Back End Server). I would like to enable the local server firewalls on the FrontEnd and BackEnd servers but when I do the Windchill randomly stops responding and I receive a "Site Status Change Notification" message saying Vaults "defaultsystemvault,defaultuploadvault" contained in this site are inaccessible because site status is "METHOD SERVER NOT RESPONDING". After 5 minutes I receive another "Site Status Change Notification" message saying that the site is reponding normally again and can continue to use the application normally. When the local server firewalls are disabled the application works perfectly with no problems.
Does anyone know why I am receiving this error or have a working set of the local Linux firewall rules that I can see as an example?
Below is an example of the "Site Status Change Notification" message I receive which shows the error and the URL it is attempting to connect to