Hi Isabella,
My name is Anthony and I am a member of the wolfSSL team. I will be helping you with this issue. This happens quite often when connecting to large web infrastructures. Please use --enable-altcertchains on your configure command line. If you don't use the confugre script, please define WOLFSSL_ALT_CERT_CHAINS in your user_settings.h .
Here at wolfSSL we love learning about how people are using our libraries. Can you please tell me a bit about yourself, your use case and any other information that would give us some context so that we can better help you?
Warm regards, Anthony