TCP over SSL issue on HL6528RD


I’m trying to open a TCP socket over SSL/TLS in order to use MQTT protocol on it.
Here below the sequence of AT commands:


Modem clock has been set via


If inside KTCPCFG command is 0 (client), TCP connection never works even if the certificate has been correctly stored. If is 3 (secure client), TCP connection always works even if I delete the certificate.

How to correctly setup a TCP over SSL socket with server authentication? Sequence of AT commands of a full working example should be really appreciated.

Thanks in advance,

I found a possible issue. The parameter <SSL profile> inside AT+KTCPCFG command seems to work only with profile 0, so if I configure a different profile (e.g. 5) with AT+SSLCRYPTO, TCP socket will be always opened with configuration 0.
If I configure profile 0 and use it as <SSL profile> and <mode> 3 (secure client), all is working as expected.

I’m using FW is there any known issues on this version about TCPCFG?


Hi @sabinocolonna,

It can be limitation of the current firmware module. In your case, I recommend that you contact your local distributor or reseller for technical support.

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