Hello yellowfin1,
The question was a bit unclear, but from what I was able to find online, it seems that CASA Systems is a company that provides support for 5G networks, and a 4 model B Raspberry Pi board has indeed 5G support.
If you have that board installed on your RS3D, then try to turn the WiFi off and see if it goes away. If now, please reformulate your question so that we can try to help you more.
Thank you.