Get Request with Basic Authentication

Hi, I want implement a simple GET request with https address and 64 bit encoded user + password on Wio Terminal. I tried with HTTPClient (rpcWifi library). When I call
curl -k -H "Authorization: Basic <encoded user+password> https://…
from a terminal, this works perfect.
I tried with “addHeader()” and got response one time when trying 20 times, 19 times the GET() function hangs/timeouts.
The examples I saw only work without “https” or with “https” plus CA certifikate. The device I want reach is in my local network.