Root Certificates for Hivemq Cloud

We are using Hivemq cloud version to test our system. We are using a TI WiFi module based on CC3235 and have to load the root certificate manually for the communication to operate.
This worked with DST CA Root X3 up to 30 9 21. We also connect to Hivemq with Python running on a PC under Windows 10.
The connection via Python on PC was re-established by manually adding ISRG Root X1 to the certificate store on the PC.
Replacing DST CA Root X3 by ISRG Root X1 on the WiFi module gives a “wrong CA root”.
Please let me know how to reconnect our IoT WiFi module to Hivemq.
Best regards