pfSense » pfSense Packages

After upgrading from pfSense Plus 25.07.1 to 25.11.x, enabling ntopng causes memory usage to grow steadily until the WebGUI becomes slow or unresponsive.

This behavior does not occur on 25.07.1 using the same configuration.

Firewall routing performance remains normal; only the WebGUI is affected.

Disabling ntopng immediately restores normal memory usage and WebGUI responsiveness.

⸻

Steps to Reproduce
1. Start with pfSense Plus 25.07.1
2. Enable ntopng (default settings)
3. Observe:
• Stable memory usage
• Responsive WebGUI
4. Upgrade to 25.11.x
5. Enable ntopng (same configuration, no changes)
6. Allow system to run normally (traffic + dashboard access)

⸻

Expected Result
• Memory usage remains stable
• WebGUI remains responsive
• ntopng does not cause system-wide UI degradation

⸻

Actual Result
• RAM usage increases significantly over time (observed ~60–70%)
• ZFS ARC grows aggressively
• WebGUI becomes slow or unresponsive
• CPU load remains low
• Firewall traffic continues to pass normally

Disabling ntopng:
• Immediately drops RAM usage (~60% → ~28%)
• Restores WebGUI performance

⸻

Diagnostic Evidence

top output during issue (ntopng enabled)

Key observations:
• CPU mostly idle
• High wired memory
• Large ARC (≈9+ GB)
• ntopng resident memory ~160 MB
• Unbound also large but unchanged from 25.07.1

Example excerpt:
CPU: ~87% idle
Mem: ~11G Wired, ~1.5G Free
ARC: ~9.4G Total (mostly MRU, heavily compressed)
ntopng RES: ~163M

Additional Notes
• ARC tunables (vfs.zfs.arc_max, vfs.zfs.arc_min) were tested but did not fully resolve the issue while ntopng was enabled.
• Identical configuration on 25.07.1 does not exhibit this behavior.
• This appears to be a regression related to memory handling / ARC interaction / WebGUI responsiveness in 25.11.x when ntopng is active.

⸻

Workarounds
• Disable ntopng
• Roll back to pfSense Plus 25.07.1

⸻

Severity

Major
Causes WebGUI unresponsiveness on otherwise healthy systems.