# FNO Troubleshooting & Fibre Diagnostics

Source: https://urbanx.co.za/knowledge-hub/fno-troubleshooting

This series covers every physical-layer fault domain you will encounter on South African fibre networks. From interpreting ONT LED sequences on Vumatel, Openserve, MetroFibre, and Frogfoot CPE units to measuring Rx/Tx optical light levels and diagnosing last-mile attenuation — each guide follows a structured fault-isolation methodology. Content is written by operational engineers with field experience across JHB and CPT metro deployments.

Long-form article: https://urbanx.co.za/knowledge-hub/fno-troubleshooting/article

## FNO-Specific Signal Guides

- [Vumatel ONT Red Light (LOS) Fix](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/vumatel-ont-red-light-los): Step-by-step fault isolation when a Vumatel ONT shows a solid or flashing red LOS indicator. Covers optical power thresholds, patch lead inspection, and FNO escalation triggers.
- [Frogfoot LOS Light Meaning & Fix](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/frogfoot-los-light-meaning-fix): Interpreting Frogfoot ONT LOS indicators and resolving optical signal faults. Includes device-specific LED reference, light-level thresholds, and escalation conditions.
- [MetroFibre Flashing PON Explained](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/metrofibre-flashing-pon): Complete LED state reference for MetroFibre CPE units. Maps each blink pattern to a specific provisioning, authentication, or optical fault condition.
- [Openserve ONT Light Status Guide](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/openserve-ont-light-status-guide): Full LED status table for Openserve ONTs — PON, LOS, LAN, and Power indicators. Covers each light state, what it means, and when to escalate to the FNO.
- [Octotel ONT Red Light Troubleshooting](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/octotel-ont-red-light-troubleshooting): Diagnosing red light conditions on Octotel ONT hardware. Includes device-specific LED meanings, optical power checks, and structured FNO escalation steps.
## Power & Hardware Integrity

- [How to Properly Restart an ONT (Without Causing Sync Delay)](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/properly-restart-ont): The correct power-cycle sequence for Vumatel, Openserve, and MetroFibre ONTs. Explains why hard resets can wipe provisioning profiles and when a 30-second wait is insufficient.
- [Does Loadshedding Damage Your Fibre Line?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/loadshedding-damage-fibre-line): How power surges and unclean shutdowns during loadshedding affect your ONT, router, and fibre signal. Covers UPS recommendations and post-outage diagnostic steps.
- [How to Check If Your Fibre Patch Lead Is Faulty](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/check-fibre-patch-lead-faulty): Visual inspection and swap-test methodology for SC/APC fibre patch leads. Covers ferrule damage, bend radius violations, and when to request an FNO replacement.
- [UPS vs Inverter: What Happens to Your Fibre Signal?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/ups-vs-inverter-fibre-signal): Comparing UPS and inverter behaviour during loadshedding and how each affects ONT uptime, sync stability, and optical signal integrity on South African fibre connections.
## Speed & Signal Issues

- [Why Is My Fibre Slow at Night in South Africa?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/fibre-slow-at-night-sa): Differentiating between FNO contention-ratio congestion and genuine line faults during peak hours. Includes time-based speed test methodology and CIR verification steps.
- [How to Test Fibre Speed Correctly (Wired vs WiFi)](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/test-fibre-speed-correctly): Why WiFi speed tests are unreliable for diagnosing fibre faults. Covers wired testing methodology, single vs. multi-thread tests, and how to isolate ISP vs. home network issues.
- [What Causes Packet Loss on Fibre?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/what-causes-packet-loss-fibre): Identifying the root causes of packet loss on South African fibre — from dirty connectors and micro-bends to FNO congestion and misconfigured QoS. Includes diagnostic commands and escalation criteria.
- [How to Run a Traceroute for Fibre Troubleshooting](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/run-traceroute-fibre-troubleshooting): Step-by-step guide to running and interpreting traceroutes on Windows, macOS, and Linux. Covers hop identification, latency patterns, and how to pinpoint the fault domain.
## Escalation Logic

- [When Should You Escalate to Your FNO?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/when-to-escalate-fno): A structured decision tree for determining whether a fault sits with the ISP, FNO, or customer premises. Reduces unnecessary escalations and speeds up legitimate fault resolution.
- [How Long Should Fibre Repairs Take in South Africa?](https://urbanx.co.za/knowledge-hub/fno-troubleshooting/how-long-fibre-repairs-sa): Expected repair timelines for each major South African FNO. Covers SLA benchmarks, escalation triggers when deadlines are missed, and what to do if your fault stalls.