Problem opening tcp socket on FC41D

Good afternoon,

I’m trying using FC41D chip on Quectel demo boards. The goal is to set one board in AP mode and another one in station mode and exchange data between them. When I try to open socket service with command


the answer is ERROR, typing QIGETERROR, the answer is

+QIGETERROR: 551,"unknown error"

Do you have suggestions?

Thank you

FC41D in AP Mode

Connect FC41D module with available AP in STA mode:


Start AP mode on module:


Start a TCP listener session on module and check the state.


FC41D in STA Mode

Connect another FC41D module with earlier started AP mode on FC41D module


Open a TCP connection as TCP client and mentioning the listener IP of FC41D_AP


TCP data communication

Send data from TCP client (FC41D STA) to TCP Listener (FC41D AP)

TCP Client:


TCP Listener:


Thank you. It’s working.
I see you use access_mode = 0 (buffer mode). It is possible to send and receive data in transparent mode?

I have firmware version FC41DAAR03A03.bin_202203110937 that I think is older than your.
Where I download the latest firmware release?

Thank you for your support

hi @Giuseppe_S
Yes , transparent mode works on TCP client.
Please share an email address to receive the firmware.