Q: “Access denied” (when using FTPS /HTTPS) to a secure (web)server.
A: Secure access depends on server implemented TLS version and Cyphers.
T: Check webserver TLS and Cypher availability can be obtained using this website:
A list with supported TLS versions and available cyphers is generated and can be used to select an valid option to build a secure connection.
On a Windows environment, openssh.exe can be installed for a command line version tool.
C:> openssl.exe s_client -connect <broker address>:<port>
The ME910G modem on a ML-417xxx Data Logger supports TLS version 1.3. (With fallback to a lower version).
Only the cyphers sets should be checked.
Other modems are supporting maximum version TLS 1.2.
The (web)server must support TLS version 1.2.
To check and change TLS version, use the COM option from maintenance menu to connect to the modem and execute AT#SSLSECCFG2. The result will show the versions.
AT#SSLSECCFG is used to select a TLS version and cypher set, matching the (web)server.