When your Sunsynk system goes offline, it’s usually due to a Wi-Fi handshake issue or a firmware “glitch” rather than hardware failure.
Here is a 2026-ready troubleshooting guide to get your monitoring back on track.
1. Decode the Logger LED Lights
The small lights on your silver Wi-Fi dongle are the fastest way to diagnose the problem.
| Light Status | What it Means | Action Required |
| No Lights at all | No power from the inverter. | Ensure the dongle is pushed in fully and the two silver screws are tight. |
| Blinking Red | Not connected to Wi-Fi. | The logger has lost your router. Follow Method 2 in the setup guide. |
| Solid Green Only | Static IP conflict. | Your router assigned the logger’s IP to another device. Reboot your router. |
| Blinking Green | Connected to Wi-Fi, but no data. | Communication issue between the logger and the inverter. Unplug/replug the logger. |
| Solid Blue/Steady Green | Normal Operation. | If the app still shows “Offline,” the issue is on Sunsynk’s server side. |
2. The “Set Fail” Error
If you are trying to reconnect and get a “Set Fail” message in the app:
- Check the Frequency: Ensure your router isn’t forcing the dongle onto a 5GHz band. Disable 5GHz temporarily or create a dedicated 2.4GHz Guest Network for the inverter.
- Whitelist the Logger: Some modern South African ISP routers (like those from Vuma or Telkom) have strict firewalls. You may need to whitelist these addresses in your router settings:
iot.e-linter.comukiot.sunsynk.net
3. The “Logger Not Found” (EAP-xxxxx missing)
If you can’t see the EAP-xxxxx Wi-Fi network when trying to do a manual setup:
- Hard Reset: Locate the tiny button on the bottom of the logger.
- Hold for 10 seconds: The lights will flash rapidly.
- Wait: Give it 2 minutes to reboot. The EAP network should now appear in your phone’s Wi-Fi list.
4. App Shows “Offline” but Lights are Normal
If your logger looks happy (Solid Blue/Green) but the Sunsynk Connect app says “Offline”:
- Server Lag: Sunsynk servers sometimes experience “refresh” delays. Wait 15 minutes.
- Check Plant Ownership: If you recently had a new installer, ensure they haven’t “unbound” your logger from your email address.
- Clear App Cache: Go to your phone settings > Apps > Sunsynk Connect > Clear Cache. This often forces the data to refresh.
5. Weak Signal (The “Phantom” Offline)
If your inverter is in a garage or behind a thick wall, it may go offline every few hours.
- The 50% Rule: The logger needs at least 50% signal strength to stay stable.
- The Fix: Use a Wi-Fi Extender placed halfway between the router and the inverter, or upgrade to the Sunsynk RJ45 Logger which allows for a stable Ethernet cable connection.
⚠️ A Note on Load-Shedding
If your router is NOT on your backup/inverter circuit, it will turn off during load-shedding. The logger will stay powered (by the inverter), but it will blink red because it has no internet to talk to. Once the power returns, it can take up to 10 minutes for the connection to automatically restore.
