11-30-2025, 07:25 PM
Hi everyone,
I just wanted to add that I am seeing exactly the same behaviour as alexps70 and apps4check on my KC868-A2 with SIM7600, using the latest KCS V2 firmware.
In my case the KC868-A2 is installed completely outside my home network – it is never connected to LAN or Wi-Fi. The board is in a remote location and has LTE-only connectivity, and my goal is to control it from Home Assistant over LTE, without any extra gateway hardware.
The SIM7600 LTE module itself works perfectly. When I connect the modem directly to a PC over USB and send AT commands, I can see that:
So the SIM card, the LTE network and the 4G hardware are all working fine.
The problem starts when the SIM7600 is used together with the KC868-A2 and the KCS firmware. As soon as I activate the GPRS / 4G option for Tuya, I see the same thing that was described above:
MQTT behaves in the same way:
It works when the A2 is connected via LAN / Wi-Fi, but as soon as the board relies on LTE only, the MQTT connection does not work anymore. From what I can see in the web UI, the GSM section only supports SMS and Call Test, and there are no APN or PDP settings and no LTE data status indicators available. This matches very well with the logs and descriptions from alexps70.
From all these tests it looks like the SIM7600 does establish a full LTE data session, but the KC868-A2 firmware does not route any Tuya or MQTT traffic over the mobile data interface. In other words: LTE seems to be limited to SMS/Call functions (and maybe Tuya on some boards), but not usable as a general data connection on the A2 right now.
For my use case this is critical, because my KC868-A2 will never be in my home LAN. It needs to work exclusively over LTE, and it needs to be controllable from Home Assistant in that mode.
So my question to the admin is:
If there is a test firmware that fixes the Tuya over GPRS problem mentioned earlier in this thread, I would be happy to test it as well.
Thank you.
I just wanted to add that I am seeing exactly the same behaviour as alexps70 and apps4check on my KC868-A2 with SIM7600, using the latest KCS V2 firmware.
In my case the KC868-A2 is installed completely outside my home network – it is never connected to LAN or Wi-Fi. The board is in a remote location and has LTE-only connectivity, and my goal is to control it from Home Assistant over LTE, without any extra gateway hardware.
The SIM7600 LTE module itself works perfectly. When I connect the modem directly to a PC over USB and send AT commands, I can see that:
- the SIM is ready
- the module registers on the LTE network
- the APN is accepted
- NETOPEN is successful
- the modem receives a valid mobile IP address
So the SIM card, the LTE network and the 4G hardware are all working fine.
The problem starts when the SIM7600 is used together with the KC868-A2 and the KCS firmware. As soon as I activate the GPRS / 4G option for Tuya, I see the same thing that was described above:
- GPRS shows “connected”, but
- Tuya stays disconnected, even if Ethernet is unplugged
- the time is not synchronized (no NTP over mobile data)
- there is no sign that LTE data is actually used
MQTT behaves in the same way:
It works when the A2 is connected via LAN / Wi-Fi, but as soon as the board relies on LTE only, the MQTT connection does not work anymore. From what I can see in the web UI, the GSM section only supports SMS and Call Test, and there are no APN or PDP settings and no LTE data status indicators available. This matches very well with the logs and descriptions from alexps70.
From all these tests it looks like the SIM7600 does establish a full LTE data session, but the KC868-A2 firmware does not route any Tuya or MQTT traffic over the mobile data interface. In other words: LTE seems to be limited to SMS/Call functions (and maybe Tuya on some boards), but not usable as a general data connection on the A2 right now.
For my use case this is critical, because my KC868-A2 will never be in my home LAN. It needs to work exclusively over LTE, and it needs to be controllable from Home Assistant in that mode.
So my question to the admin is:
- Does the KC868-A2 firmware currently support using the SIM7600 LTE data connection for Tuya and/or MQTT at all?
- If yes, which firmware version or configuration is required to make this work, especially in a setup where the device has no LAN/Wi-Fi available and must run LTE-only?
If there is a test firmware that fixes the Tuya over GPRS problem mentioned earlier in this thread, I would be happy to test it as well.
Thank you.