Not sure what the mistake here was…
There are 4 Access Points being controlled by caps-man.
/caps-man actual-interface-configuration disable [find configuration.ssid~"Guest"]
Running that turned off the Virtual APs that provided the guest network
However… it also turned off the WAN interface.
The Wan interface is simply ether1-WAN.
Doesn’t make sense to me.
RouterOS 6.43.2