The exhibit shows a FortiGate configuration under config system fortiguard related to web filtering and FortiGuard options. There is a line:
set webfilter-force-off enable
According to official Fortinet documentation, the "webfilter-force-off" option, when enabled, causes the FortiGate to bypass web filtering for all traffic-even if a web filter profile is applied to a policy. This override is typically used for troubleshooting or performance reasons and is documented as an explicit bypass feature.
If an administrator wants to enforce web filtering inspection, this setting must be disabled. The correct way to restore web filtering functionality is to run:
set webfilter-force-off disable
Once done, traffic passing through policies with web filter profiles will be inspected and filtered as per configuration. Other settings such as timeout or cache TTL do not bypass web filtering; they only affect operational nuances.
Reference:
FortiOS Administration Guide: Web Filtering, FortiGuard Options, "webfilter-force-off" CLI

The partial output from diagnose hardware sysinfo memory provides details on system RAM allocation. According to Fortinet's technical documentation for memory troubleshooting and Linux memory management (which FortiOS is based on):
MemFree is the portion of physical memory not currently allocated to any running process or kernel function. Thus, 708880 kB is available and can be immediately used by user-space programs or system operations.
Inactive refers to pages in the memory cache that were previously in use for I/O or file system buffering but are now not actively referenced. These pages are retained in memory for quick access if needed again, but can be reclaimed for other memory operations if demand increases. The value 98908 kB here represents currently unused cache pages (inactive pages), ready for repurposing or deletion if the system requires more RAM.
Cached represents the total amount of system memory allocated to cache, which includes both active and inactive cache pages. It does not, by itself, represent I/O cache exclusively, nor does "inactive" mean memory "will never be used" as the kernel can re-purpose inactive pages on demand.
References:
Fortinet Technical Tip: Explaining the 'diagnose hard sysinfo memory' command FortiOS System Administration Guide: Linux Memory Reporting, Cached and Inactive Statistics

The issue is caused by the strict matching logic of the configured Prefix List.
Current State: The rule is edit 1 with set prefix 172.16.0.0 255.255.0.0 and both ge (greater than or equal) and le (less than or equal) are unset.
Behavior: When ge and le are unset, FortiOS requires an exact match of the subnet mask. The current rule only matches the exact network 172.16.0.0/16. It denies 172.16.52.0/24 because the mask (/24) does not match the rule's mask (/16).
To fix this and inject 172.16.52.0/24, you must modify the list to match the /24 mask:
A). Add another entry to the prefix list to specifically allow the 172.16.52.0/24 network:
Creating a new rule (e.g., edit 2) with set prefix 172.16.52.0 255.255.255.0 will provide an exact match for the incoming route, allowing it to pass the distribute-list.
B). Change the ge value to 17:
By configuring set ge 17 on the existing rule (conceptually 172.16.0.0/16 ge 17), you change the logic from
"exact match" to "range match".
This configuration tells the router to match any prefix starting with 172.16.x.x that has a subnet mask length of 17 or greater.
Since the incoming route is a /24, and 24 is greater than 17, the route will match the prefix list and be accepted.
Why other options are incorrect:
C: The option text appears to read "Change the ... value to 16". If this refers to le 16, it would enforce the mask to be exactly /16 or less, which still excludes /24.
D: Changing the default behavior to implicit allow defeats the purpose of a filter (security control) and is not a standard configuration step for fixing a single missing route.
Reference:
FortiGate Security 7.6 Study Guide (Routing): "In prefix-lists, if ge and le are not used, the subnet mask must match exactly. To match subnets within a range, you must define the prefix length boundaries using ge or le."

The debug flow message iprope_in_check() check failed, drop specifically indicates a failure in the Local-In Policy check. The " iprope " (IP ROouting Policy Enforcement) engine handles policy lookups. The
_in_check suffix confirms that the decision is regarding traffic destined to the FortiGate itself (Local-In traffic), rather than traffic passing through it.
D). The packet was dropped because the requested service is not enabled on FortiGate:
This is the most common cause. When a packet arrives destined for the FortiGate ' s interface IP (e.g., an HTTPS or SSH request), the kernel checks if that specific service is enabled in the interface settings (set allowaccess). If the service is not enabled (e.g., trying to Ping an interface where PING access is disabled), the iprope_in_check function fails and drops the packet immediately.
C). The packet was dropped because the trusted host list is misconfigured:
Even if the service (e.g., HTTPS) is enabled on the interface, the FortiGate checks the Administrator settings.
If Trusted Hosts are configured, the source IP of the incoming packet is compared against the allowed list. If the IP is not on the list, the Local-In policy check (iprope_in_check) fails, and the packet is dropped to secure the management plane.
Why other options are incorrect:
A: If traffic is dropped by a standard Firewall Policy (traffic passing through the device from one interface to another), the debug message will typically state denied by policy x or no matching policy. It would generally be a forward check (iprope_fwd_check or similar), not an _in_check.
B: If there is no route to the source, the error is a Reverse Path Forwarding (RPF) failure. The debug flow logs this explicitly as reverse path check fail, drop.
Reference:
FortiGate Troubleshooting Guide (Debug Flow): " The message iprope_in_check() check failed indicates the packet was denied by the Local-In policy. This occurs when traffic destined to the FortiGate is not allowed by the allowaccess configuration or is blocked by Trusted Host settings. "

The partial output from diagnose hardware sysinfo memory provides details on system RAM allocation.
According to Fortinet's technical documentation for memory troubleshooting and Linux memory management (which FortiOS is based on):
MemFree is the portion of physical memory not currently allocated to any running process or kernel function.
Thus, 708880 kB is available and can be immediately used by user-space programs or system operations.
Inactive refers to pages in the memory cache that were previously in use for I/O or file system buffering but are now not actively referenced. These pages are retained in memory for quick access if needed again, but can be reclaimed for other memory operations if demand increases. The value 98908 kB here represents currently unused cache pages (inactive pages), ready for repurposing or deletion if the system requires more RAM.
Cached represents the total amount of system memory allocated to cache, which includes both active and inactive cache pages. It does not, by itself, represent I/O cache exclusively, nor does "inactive" mean memory
"will never be used" as the kernel can re-purpose inactive pages on demand.
References:
Fortinet Technical Tip: Explaining the 'diagnose hard sysinfo memory' command FortiOS System Administration Guide: Linux Memory Reporting, Cached and Inactive Statistics