Zyxel Nebula 5G Routers FWA Series - Advinced Troubleshooting and Improving LTE/5G Signal Quality

This article will explore the key signal quality parameters for Zyxel FWA series routers, including the FWA505, FWA510, and FWA710 models. We will explain in detail the important metrics for evaluating LTE and 5G signal quality, how to optimise these parameters to enhance network performance, and how the device's placement and external conditions can impact the signal. Additionally, we will provide recommendations for improving signal quality to achieve maximum speed and connection stability.

Note: At this time, the Zyxel Air app does not support the FWA505 model. We are already working on adding support, and it will be available in one of the upcoming updates.

Signal parameters

RSRP (Reference Signal Received Power):
RSRP measures the strength of the signal received from the base station. Higher values indicate a stronger signal, leading to better network performance, while lower values result in weaker signals and potential connection issues.

RSRQ (Reference Signal Received Quality):
RSRQ measures the quality of the signal by comparing its strength to interference and noise. Higher values indicate better signal quality, while lower values suggest more interference and poorer performance.

SINR (Signal to Interference plus Noise Ratio):
SINR compares the signal strength to noise and interference. Higher values represent a cleaner signal with minimal interference, while lower values lead to slower speeds and less stable connections.

Upgrade to the Latest Equipment

• Ensure the device supports the latest LTE/5G bands and technologies.
• Consider upgrading to a device with better signal reception and stronger antennas.

How to improve signal performance

Zyxel Air helps you find the best placement and direction to improve signal quality.

Attention: The latest version of the Zyxel AIR app currently does not support the Zyxel FWA505. We are actively working on enhancing our application, and this functionality will be restored in a future update.

Zyxel Air: Signal Optimisation and Troubleshooting for FWA Devices

Optimal Device Placement

⚠️ Note: These placement recommendations apply to FWA505 and FWA510 models.
The FWA710 uses an external antenna and may require a different approach for optimal positioning.
For detailed placement and installation guidance for FWA710, please refer to the official instructions here.

• Place the device in an open area with minimal obstructions.
• Keep the device away from walls, metal surfaces, and large electronic devices that could cause interference.
• For 5G devices, positioning near windows may help improve signal reception.

The two screenshots below show the cellular signal statistics of the same Zyxel FWA device placed in two different locations:

• Center of the room (Screenshot 1)
• Near a window (Screenshot 2)

Simply moving the device closer to a window led to a noticeable improvement in signal strength and quality:

• RSRP improved from -102 dBm to -92 dBm
• NR SINR jumped from 10 dB to 18 dB
• RSSI increased by 11 dB

This small adjustment significantly enhances the connection’s reliability and speed. It clearly demonstrates that optimal placement—preferably near windows or with line-of-sight to the nearest base station—can greatly improve performance, especially for 5G.

Here's a detailed comparison of the two screenshots for Zyxel FWA cellular signal data:

Summary:

Screenshot 2 shows a clear improvement in signal strength and quality:

• Stronger RSSI, RSRP, and NR RSRP
• Higher NR SINR (better signal clarity)
• Minor drop in LTE SINR and slightly worse RSRQ, but overall quality is significantly better.

This could result from better antenna placement, less interference, or improved network conditions.

Use External Antennas

• Use high-gain external antennas to boost signal strength, especially in areas with weak coverage.
• Directional antennas can be more effective if you know the direction of the nearest base station.

Regular Firmware Updates

• Firmware updates often include security patches, stability improvements, and performance enhancements. In some cases, updates may also contain modem (radio module) updates, which can improve connectivity, signal quality, and overall device performance.

  You can find the latest firmware for your Zyxel device in our official Download Library

Switch to a Different Frequency Band

• Some LTE/5G networks have multiple frequency bands. Switching to a less crowded or less congested band may improve performance.

  Zyxel FWA Series [5G Signal] - Cellular Band & Achieving a Good Signal

Check Coverage and Network Availability

• Inquire about network coverage in your area. Signal issues may be due to insufficient coverage from your provider in your location.
• Ensure your area supports LTE or 5G networks. 5G coverage may be limited in some regions, and your provider may not have equipment in your zone.

Inquire about network coverage in your area.
Signal issues are often caused by insufficient LTE or 5G coverage. Check your provider’s coverage map, or contact their support to confirm network availability and supported bands in your location.

Use apps like CellMapper or OpenSignal to detect nearby towers and signal type.
This step is critical to ensure your device can operate at full capacity — even the best hardware won’t help if coverage is lacking.

Please refer to the signal coverage map: https://www.nperf.com/en/map/

Zyxel FWA Router [LTE / 5G] - Issues Zyxel vs. Provider Issues

Cellular Lock

• The Cellular Lock feature allows certain Zyxel devices to restrict their connection to a specific cell tower, which can be beneficial in environments with multiple base stations. However, this feature is supported only on select models like the NR7101 and FWA710.

Zyxel FWA Series [5G] - Cellular Lock

Check for Network Overload

• Inquire if the network is overloaded in your area, particularly during peak hours. Network congestion can cause slow speeds and unstable signals.

Check for Network Overload
Test your connection at different times of day — if speed drops noticeably during evenings, the network may be congested. You can also ask your provider if there’s known overload in your area. In Zyxel devices, low or fluctuating SINR values may also indicate congestion.

Consider Switching Providers

• If signal quality issues persist despite all adjustments, you may consider testing a SIM card from another provider to evaluate whether better coverage or performance is available in your area. This can help determine if changing providers would lead to a more stable connection.

Carrier Grade NAT

Having trouble with remote access or port forwarding? The issue might be caused by Carrier-Grade NAT (CGNAT). Learn how to check and fix it — LTE / 5G Routers - Explaining Carrier Grade NAT

Data Roaming

When to check:

• SIM from another country or operator
• Good signal but no internet
• SIM works in other devices, but Zyxel shows “connected” without access

Why:
If roaming is off, the device may block mobile data outside the home network.

What to do:

• Go to the GUI:
  Menu > Network Setting > Broadband > Cellular WAN
• Make sure Data Roaming is enabled
• Or via CLI:
  cfg cellwan get
  Check that "DataRoaming": true

Why it matters:
If roaming is disabled, the device won't be able to connect to mobile internet when using a SIM card outside its home network or country.

PLMN (Manual Network Selection)

What to do:

• GUI: Menu > Network Setting > Broadband > Cellular PLMN
• Disable Auto Selection and click Scan
• Choose the correct network manually

⚠️ Note: Disabling auto selection will temporarily disconnect the network (including SSH).

Why it matters:
Useful when automatic selection connects to the wrong network or fails to connect at all.

Band and Access Technology

What to do:

• GUI: Menu > Network Setting > Broadband > Cellular Band
• Make sure the appropriate bands are enabled and correct access technologies (e.g., LTE, 5G) are selected
• CLI:
  cfg cellwan_band get — to check current settings

Why it matters:
If the selected bands or technologies don't match what's available from the operator, the device may not detect or connect to the network.

Recommendations

• Reboot the device after making changes
• If issues persist, collect logs and contact technical support