Issue Accessing Qlik Sense Hub

[awhitfield]

Afternoon, some of our users but not  all are getting the below error message, which I understand to normally be an issue with the web service but as this error is being encountered sporadically by some of our users I am wondering if we have a certificate issue with our Qlik Sense install. Please could you advice as to what this might be?

[vinieme12]

check the first one

Error 500 in qlik sense

Error 500 - Internal Server Error

[Anonymous]

It must be port issue with the proxy service. Check both inbound and outbound are open.