[Bug]: Cannot reconnect to S5-WiFi-ST after Home Assistant and integration update

[sirenkovv]

🐛 Bug Description

🐞 Bug Description

After updating both Home Assistant and the Solis Modbus integration, the integration stopped working correctly.

Initially, the integration remained loaded, but all inverter values stopped updating and appeared to be frozen at the last received values.

To resolve the issue, I removed the integration from Home Assistant. Since then, I have been unable to add it again. During the setup process, I always receive the following error:

Cannot connect to Modbus device. Please check your configuration.

The inverter and logger continue to work normally with SolisCloud, so the issue appears to be limited to the Home Assistant integration.

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🔄 To Reproduce

1. Update Home Assistant and the Solis Modbus integration.
2. Observe that inverter data stops updating in Home Assistant (values remain frozen).
3. Remove the integration.
4. Try to add the integration again using the same configuration (TCP / Modbus port 502).
5. The configuration always fails with:

Cannot connect to Modbus device. Please check your configuration.

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✅ Expected Behavior

The integration should reconnect successfully to the logger and continue updating inverter data via Modbus TCP, as it did before the update.

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📸 Screenshots / Logs

I can provide:

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🔧 System Information

🔹 Home Assistant

• Version: (please fill in)
• Installation Method: (please fill in)

🔹 Integration

• Plugin Version: 4.1.5 (also tested 4.1.6)
• Inverter Model: Solis S5-30GC
• Logger Model: S5-WiFi-ST
• Connection Type: Modbus TCP (Wi-Fi)
• Logger IP: 192.168.31.211

• Custom Config Entries: No

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➕ Additional Context

I have already tried the following:

• Restarted Home Assistant.
• Restarted the router.
• Restarted the S5-WiFi-ST logger.
• Removed and reconfigured the logger's Wi-Fi connection.
• Unbound and rebound the logger to the inverter.
• Tested both integration versions 4.1.5 and 4.1.6.

None of these steps resolved the issue.

The logger itself appears to be working correctly:

• The inverter continues uploading data to SolisCloud without interruption.
• I can access and modify inverter settings through SolisCloud.
• Communication between the inverter and the logger appears normal.

The issue only affects the Home Assistant integration. After removing the integration, I can no longer add it back because the Modbus connection test always fails.

Please let me know if there are any additional logs or diagnostic tests that would help identify the cause.

I also noticed that the logger no longer appears to expose any local network services.

From a PC on the same LAN:

ICMP ping to 192.168.31.221 is successful.
TCP port 502 (Modbus) is not reachable.
HTTP (port 80) is also not reachable.
Test-NetConnection confirms that TCP port 502 is closed or not accepting connections.

Since the logger is online and continues communicating with SolisCloud normally, I am wondering whether:

a recent logger firmware update may have changed or disabled local Modbus TCP access,
the logger firmware could have become corrupted,
or there is another configuration that enables/disables local Modbus TCP.

Could you please check whether the logger has recently received a firmware update and whether Modbus TCP should still be available on port 502 for this firmware version?

PowerShell:
Test-NetConnection 192.168.31.221 -Port 502
PingSucceeded : True
TcpTestSucceeded : False

[sirenkovv]

I would like to provide an update regarding the issue with port 502 on the Solis Logger.

Since I was unable to access the Modbus TCP port (502) through the original Solis logger, I implemented an alternative solution by connecting an Elfin EW11 to the inverter's RS485 interface and configuring Modbus TCP communication through it.

After installing and configuring the Elfin EW11, communication with the inverter is working properly, Modbus registers can be read successfully, and the integration with Home Assistant operates without any issues.

[ptrdom]

I have the same issue, wrote to Solis support, they said I should get S2-WL-ST, but I can also find same issue reported of all open ports disappearing with S2-WL-ST as well. Overall I think this is a OTA firmware update issue on the datalogger, nothing to do with the integration or HA - they would not be able to close ports on the datalogger. Since S2-WL-ST product page does report modbus TCP support - unlike S5-WiFi-ST, at least you would be able to complain to Solis.

[giceton]

Just wanted to drop by to say I'm having this exact same issue and so far I'm getting nowhere with Solis

[devnull0111]

Any news? S2-WL-ST not working

[giceton]

I've had to give up and create use a stand alone modbus to TCP bridge and to be honest I wish I had done this in the first place as I've no need for Solis cloud

[sirenkovv]

I continue to use the Elfin EW11 with Home Assistant instead of the original S5-WiFi-ST. However, I haven't seen any communication from Solis acknowledging that Modbus is no longer working. That's quite disappointing.

[Nino6689]

@sirenkovv's PowerShell test is the answer here, and it rules the integration out:

Test-NetConnection 192.168.1.221 -Port 502
PingSucceeded      : True
TcpTestSucceeded   : False

That's from a PC with no Home Assistant involved, and port 80 is down too — the logger's own web UI. Nothing in an HA integration can close ports on a datalogger. Add that the same integration build works perfectly for you through an Elfin EW11, and it's conclusive: this is datalogger firmware dropping its local TCP services while the cloud uplink keeps working. @ptrdom reached the same conclusion independently.

So I can't fix the cause. What I can fix is that the integration made it needlessly hard to find — "Failed to connect, please check your settings" sends people hunting host, port, slave and model for days when the real answer is that nothing is listening.

#442 adds a plain TCP probe before the Modbus handshake, so a closed port now reports itself as a closed port, names the likely cause, and suggests an RS485-to-TCP bridge — and fails fast instead of grinding through Modbus timeouts. There's also a README troubleshooting entry with the Test-NetConnection / nc -vz check so people can confirm it themselves in ten seconds.

For anyone hitting this: the workarounds that have actually worked in this thread are an Elfin EW11 or a Waveshare RS485-to-Ethernet bridge on the inverter's RS485 port, or a direct USB RS485 adapter using the serial connection type. All bypass the logger.

Worth pressing Solis on it — the S2-WL-ST product page does advertise Modbus TCP support.

Separately, and worth flagging for anyone landing here: v4.1.6 is still the latest release while master carries 30 commits, including a repair issue that surfaces exactly this failure and the config-flow hardening above. Those fixes aren't reachable via HACS yet.

[giceton]

Hi. Completely agree - this is a Solis issue, not the add on. I had thought of this thread as a discussion about the issue in general rather than specific to the integration. Which was a bit stupid given where we're having the discussion 🤣 thanks for the improvement to help pinpoint the issue though, and for the integration itself! If there's a link to a "buy me a coffee" or similar please post it so I can show my appreciation

[Pel1can111]

I have a S2-WL-ST that is currently still working. The firmware reported on the Solis site is 100141d9. Curious what the version is that is not working?

I upgraded to a S2-WL-ST 2 months ago and it was fully updated by Solis at that point. I know at the time this killed the local web interface and Solis confirmed they removed that.

EDIT: I also just realised the S2-WL-ST can be accessed over Bluetooth through the solis app, this allows MQTT to still be used now that the web interface has been removed. It might be worth checking this and seeing if there is any mention of modbus on updated devices.