Cant connect to Inverter or SDongle for 2 years

[flrnwrzl]

I’ve been facing a persistent issue for the past two years and haven’t been able to resolve it. Despite searching through numerous threads and blogs, I haven’t found a solution that works.

Issue Description
When I initially installed my Huawei Inverter 8KTL-M1 with a Luna battery and SDongle, I was able to connect to the inverter without any problems. However, at some point (I’m not sure exactly when), the connection was lost, and since then, I have never been able to reconnect.

Current Setup & Status
Network Connection: Attempting to connect via LAN/Wi-Fi.
Ports: 502 and 6607 are open (confirmed via ping).
IP Configuration: All components have fixed IP addresses.
Modbus: Unrestricted mode is enabled in FusionSolar.
Firmware: All devices are up to date.
Troubleshooting Steps Taken
I have tested various configurations, but nothing has worked:

Tried connecting to both Inverter and Dongle using:

• IP: Fixed IP address
• Ports: 502 / 6607
• Slave ID: 0 / 1

Attempted different connection methods:

• Direct Wi-Fi connection from Home Assistant (HA) to Inverter

• Direct Wi-Fi connection from HA to Dongle

• Performed tests with and without elevated permissions.

• Tried with and without the SDongle connected.

• Restarted all devices multiple times.

• Changed fixed IP addresses.

• Reinstalled Home Assistant (HA) from scratch.

• Removed and reinstalled the Huawei integration from HACS.

• Restarted HA after each step.

Error Logs & Observations
One of the most notable errors I encountered was:
"Modbus connection interrupted by another device."

• I am aware that Huawei inverters allow only one Modbus connection at a time, but I’m not aware of any other device currently accessing it.

• I have already contacted Huawei support, but they were unable to provide a clear explanation or a solution.

Please find attached some logs
errors.txt
modbus_log.txt

Does anyone have suggestions on what else I can try?