This read-write disable/enable attribute controls whether the ComController automatically pushes the hcxStuAltDownFreq value to any unconfigured ComPort it acquires, and it cannot be enabled if hcxStuDefaultAuth is true or hcxStuAltDownFreq is still 0. An admin uses this to steer newly discovered, unconfigured modems onto a separate frequency automatically rather than manually reassigning each one. For example, an admin's SNMP set of this attribute to enable fails until they first set hcxStuDefaultAuth back to false, illustrating the documented mutual-exclusion between the two features.