What does the diamond network/wifi icon mean?

Periodically throughout the day when I am using Universal control from my MacBook to my Mac mini, I will lose connection and this odd diamond network/wifi icon will show up and I have to turn wifi off and back on again to reestablish the universal control connection.

Can anyone shed some light on why this is happening and what I can do to prevent it? Both the MacBook and the Mac mini are in the same room as the access point, they both have bluetooth turned on, they both are on the latest OS version.

Thanks!