Access Denied at QB Time

Two weeks ago, we started experiencing "Access Denied" errors when trying to log into our Timesheet application. Initially, we suspected the issue was related to our firewall, as we had recently made changes. We added exception rules in our FortiGate firewall, but the issue soon affected remote users as well—users who do not go through our office firewall. We've also tested access using different browsers (Chrome, Edge, and Firefox) to rule out browser-specific issues, but the results have been inconsistent.

Occasionally, the problem resolves itself temporarily without any changes on our end. We are heavily dependent on this application both internally and for our clients, as it is essential for reporting work hours. Any guidance or suggestions would be greatly appreciated.