Troubleshooting — 4G Connectivity
This guide helps you diagnose and resolve 4G/LTE connectivity issues on your Eziwan Gateway. Cellular connectivity is often the primary cause of downtime—this guide covers 95% of the cases encountered in the field.
Understanding Signal Indicators
Before making a diagnosis, it is essential to understand cellular signal metrics.
Key Metrics and Target Values
| Metric | Meaning | Excellent | Good | Acceptable | Insufficient |
|---|---|---|---|---|---|
| RSSI (dBm) | Received signal strength | > -65 | -65 to -75 | -75 to -85 | < -85 |
| RSRP (dBm) | LTE reference signal strength | > -80 | -80 to -95 | -95 to -105 | < -105 |
| RSRQ (dB) | Reference Quality | > -10 | -10 to -15 | -15 to -20 | < -20 |
| SINR (dB) | Signal-to-Noise Ratio | > 20 | 13 to 20 | 0 to 13 | < 0 |
Access Signal Metrics
From the gateway's web console:
Menu: Network → Cellular Status → Signal Details
From the gateway's REST API:
curl http://192.168.1.1/api/v1/modem/signal
# JSON response:
# {"rssi": -72, "rsrp": -89, "rsrq": -12, "sinr": 15, "band": "B3", "operator": "Orange"}
Problem 1: No 4G connection — SIM not recognized
Symptom: Red SIM LED is steady; no network is registered.
Causes and Diagnosis
Check 1: SIM card is inserted correctly
The gateway uses a Nano-SIM (4FF) format. Make sure the SIM card is inserted all the way until it clicks into place, with the metal contacts facing down. Turn off the gateway, then remove and reinsert the SIM card.
Verification 2: SIM card with PIN enabled
A SIM card with a PIN that has not been configured in the gateway will be rejected. To disable or configure the PIN:
Menu: Network → SIM → PIN Settings
It is recommended that you disable the PIN on industrial SIM cards to prevent them from being locked after a reboot.
Check 3: SIM card activated by the carrier
A new SIM card may require manual activation (making the first call from a phone or activating it on the carrier's website). Test the SIM card in a smartphone to confirm that it is active.
Check 4: SIM card not on a plan or blocked
If the SIM card has exceeded its data limit or if the account is past due, the data connection will be blocked. Check the status on your carrier's portal.
Problem 2: SIM card is registered but there is no data connection
Symptom: Green SIM LED flashing (registered on the network) but no data traffic.
Main cause: Incorrect APN
The APN (Access Point Name) is required to establish a data session. Each carrier has its own APN.
APN for the major French carriers:
| Carrier | Consumer APN | M2M/IoT APN |
|---|---|---|
| Orange | orange.fr | m2minternet |
| SFR | sfr | gprsinternet |
| Bouygues Telecom | mmsbouygtel.com | b2bouygtel.com |
| Free Mobile | free | free |
| Transatel / MVNO | Provided by MVNO | Provided by MVNO |
| Eziwan multi-operator SIM | eziwan.m2m | Pre-configured |
To configure the APN:
Menu: Network → Cellular Profiles → APN
Configuration example:
Nom profil : Orange M2M
APN : m2minternet
Type auth : PAP/CHAP
User: (leave blank if not required)
Password: (leave blank if not required)
Problem 3: Weak Signal — Insufficient Data Rate
Symptom: RSRP < -105 dBm, data rate < 1 Mbps, unstable connections.
Solution 1: External Antenna
The gateway comes with an internal antenna. In areas with weak signal strength, an external antenna significantly improves performance.
Recommended antennas:
| Type | Gain | Application |
|---|---|---|
| Magnetic whip antenna | +3 dBi | Metal cabinet (Faraday cage effect) |
| Directional antenna | +8 to +12 dBi | Very remote location, long range |
| Outdoor marine antenna | +5 dBi | Outdoor use, UV- and weather-resistant |
| 2×2 MIMO antenna | +5 dBi | Optimized for LTE Cat.4+ data rates |
The gateway has 2 SMA connectors (main + diversity). To optimize MIMO performance, connect an antenna to each port.
External antenna connection:
ANT-MAIN Port → Main Antenna (signal + data rate)
ANT-DIV Port → Diversity Antenna (Stability + MIMO)
Solution 2: Physical Repositioning
The gateway's location in the electrical cabinet affects the signal:
- ✅ Non-metallic cabinet or exterior wall → nominal signal
- ⚠️ Closed metal cabinet → attenuation of -10 to -20 dB (requires an external antenna)
- ✅ Height → higher = better signal (avoid basements)
Solution 3: Switch to a different LTE band
Depending on your carrier and your location, certain LTE bands offer better performance:
| LTE Band | Frequency | Range | Penetration |
|---|---|---|---|
| B20 (800 MHz) | 791–862 MHz | Excellent | Excellent |
| B3 (1800 MHz) | 1710–1880 MHz | Good | Good |
| B1 (2100 MHz) | 1920-2170 MHz | Average | Average |
| B7 (2600 MHz) | 2500-2690 MHz | Poor | Poor |
For rural areas and buildings, use the B20 band (800 MHz) if available:
Menu: Network → Advanced Settings → LTE Bands → Force B20 Only
Problem 4: Dual SIM failover does not trigger
Symptom: The primary SIM card fails, but the gateway does not switch to the secondary SIM card.
Failover Configuration
Dual SIM failover must be explicitly configured:
Menu: Network → SIM → Dual SIM Management
Recommended settings:
Mode SIM : Failover automatique
SIM principale : SIM1
SIM secondaire : SIM2
Méthode détection : Ping (URL de test : 1.1.1.1)
Intervalle ping : 30 s
Seuils failover : 3 pings perdus consécutifs
Retour SIM principale : Oui, après 5 min de stabilité
Manual failover test:
Menu: Network → SIM → Force SIM2 Switch
Verify that SIM2 is active, has data, and that its APN is configured correctly (a backup SIM without the correct APN will be useless during an actual failover).
Typical Failover Times
| Configuration | Failover Time |
|---|---|
| Fast failover (10-second ping, 2 failures) | ~25 s |
| Standard failover (30-second ping, 3 failures) | ~95 s |
| Conservative failover (60-second ping, 5 failures) | ~305 s |
For mission-critical applications, use the "Fast Failover" configuration.
Problem 5: Logout After a Period of Inactivity
Symptom: The gateway disconnects from the 4G network after X minutes without active traffic.
Cause: NAT/operator session timeout
4G operators close inactive data sessions after a certain period of time (usually 5 to 30 minutes). Without a keepalive mechanism, the gateway loses its session.
Solution: Keepalive enabled
Set up a regular ping to an external server to keep the session active:
Menu: Network → Keepalive → Enable
Target URL: 1.1.1.1 (Cloudflare) or 8.8.8.8 (Google)
Intervalle : 60 s
This option sends an ICMP ping every 60 seconds, keeping the operator's NAT table active.
Alternative Solution: OpenVPN Keepalive
The OpenVPN tunnel includes its own keepalive mechanism, which also maintains the 4G session:
# .ovpn file: ping every 25 seconds, restart after 120 seconds without a response
keepalive 25 120
If the OpenVPN tunnel is active with keepalive 25 120, no additional keepalives are required.
Problem 6: Insufficient 4G Speed for My Needs
Symptom: The measured data rate is well below the theoretical LTE Cat.4 data rate (150 Mbps).
Typical Actual Data Rates by Scenario
| Scenario | Actual download speed | Eziwan usage |
|---|---|---|
| Dense urban area, good coverage | 30–80 Mbps | More than sufficient |
| Suburban area, good coverage | 10–30 Mbps | Sufficient |
| Rural area, adequate coverage | 2–10 Mbps | Sufficient |
| Remote area, weak signal | 0.5–2 Mbps | Sufficient for Modbus/MQTT/VPN |
| White spot (2G/EDGE only) | 0.05–0.1 Mbps | Insufficient for VPN; Modbus only |
Required data speeds for Eziwan services:
| Usage | Minimum Data Rate | Recommended Data Rate |
|---|---|---|
| Modbus data collection (100 registers, 1 s) | 10 Kbps | 50 Kbps |
| MQTT telemetry (1,000 messages/min) | 100 Kbps | 500 Kbps |
| TIA Portal / Step 7 VPN access | 512 Kbps | 2 Mbps |
| Graphical HMI VPN access | 1 Mbps | 5 Mbps |
| PLC firmware update | 1 Mbps | 10 Mbps |
Even a speed of 1 Mbps is sufficient for 95% of Eziwan's industrial applications.
Operator Decision Table by Zone
| Geographic Area | Recommended Carrier (SIM1) | Backup Carrier (SIM2) |
|---|---|---|
| Île-de-France | Orange or SFR | Bouygues |
| Major cities | Orange or SFR | Free |
| Rural Areas | Orange (best B20 coverage) | Bouygues |
| Industrial Areas (uncovered areas) | Eziwan Multi-Operator SIM | Orange |
| Alps, Mountainous Areas | Orange | SFR |
| Brittany, Coast | Orange | Bouygues |
Tip: For critical deployments in rural areas, use the Eziwan multi-carrier SIM (included with the Business subscription), which automatically switches between Orange, SFR, and Bouygues depending on signal strength.
Quick 4G Troubleshooting Checklist
- SIM LED steady green (data active)
- APN correctly configured for the carrier
- SIM PIN disabled or configured in the gateway
- RSRP > -105 dBm (sufficient signal)
- LTE band appropriate for the area (B20 for rural areas)
- External antenna installed if in a metal cabinet
- Dual SIM failover configured with APN on SIM2
- Keepalive active (OpenVPN
keepalive 25 120) - SIM active with the carrier (check carrier portal)
- Data quota not exceeded
Advanced Diagnostic Commands
From the gateway's SSH console (accessible via the Eziwan portal):
# Statut connexion cellulaire
mmcli -m 0 --simple-status
# Detailed Signal Information
mmcli -m 0 --signal-get
# Forcer une reconnexion
mmcli -m 0 --simple-disconnect && mmcli -m 0 --simple-connect
# List available networks (scan)
mmcli -m 0 --3gpp-scan
# Real-time modem logs
journalctl -u ModemManager -f
If you have any questions not covered in this guide, please contact Eziwan technical support at support.eziwan.com.
Frequently Asked Questions
How should RSRP and RSRQ be interpreted?
RSRP (signal strength): > -90 dBm—excellent; -90 to -105—fair; < -110—critical. RSRQ (quality): > -10 dB—good; < -15 dB—poor. A fair RSRP combined with a poor RSRQ indicates interference or an overloaded cell.
The SIM card isn't detected. What should I do?
Turn off the power before performing any operations, check the insertion direction and the clip on the SIM holder, and clean the contacts. If the SIM is detected but won't connect, check the APN and verify that the line is activated via the SIM console.
Which camera should I set up?
With the included M2M SIM card, none: the APN is preconfigured. If using a third-party SIM card, enter the operator’s exact APN (and any required credentials) in the device’s network profile—a typo in the APN is the number one cause of connection failure.
The signal is weak inside the metal cabinet—what are my options?
In order of effectiveness: antennas mounted outside the cabinet, a high-gain outdoor antenna pointed toward the relay, and a multi-carrier SIM card to connect to the network with the strongest local signal.
Related Resources
- Continuously Monitor RSRP/RSRQ — the go-to article
- Multi-carrier M2M SIM — resilient connectivity
- IoT SIM card — choosing the right SIM for your devices
- Troubleshooting remote access — if the VPN is the issue
- Eziwan Support — open a ticket with the diagnostics