Nano CH340G + SIM7600E-H: LTE insufficient signal despite strong network availability

I can't see this error information :

Opening pass.telekom.de 1 provides additional information.

So I can't see the explanation for the failure of the HTTP connection. You have to be in a telekom.de network to see it.

I notice that no example setup parameters for telekom.de are included in the test sketch:

//----------------------------------------------------------------
// Allgemeine Konfiguration
//----------------------------------------------------------------

// LTE Konfiguration

// Name des Zugangspunktes des Netzwerkproviders
//const char APN[] PROGMEM = {"internet.t-mobile"};
//const char APN[] PROGMEM = {"web.vodafone.de"};
//const char APN[] PROGMEM = {"internet.eplus.de"};
const char APN[] PROGMEM = {"APN"};

// Benutzername des Zugangspunktes
static char APN_Benutzer[] = {""};  // vodafone ohne APN-Benutzer/Passwort
//static char APN_Benutzer[] = {"t-mobile"};
//static char APN_Benutzer[] = {"eplus"};
// Passwort des Zugangspunktes
static char APN_Passwort[] = {""};
//static char APN_Passwort[] = {"tm"};
//static char APN_Passwort[] = {"eplus"};

What values did you give for these APN variables ?

There is a stack of SIMCOM product documentation here: Technical Files. You can narrow the search to SIM7600X . You have to register to be able to download files (which I have not done).

SSL can fail if there is a certificate problem. I suppose you could look at updating the firmware in the module which may bring in some fresh root certificates.

You may also ask telekom.de if the specification of the SIM7600E-H matches their network and about any special parameter issues.