SXK80 AP Mode: Disable captive portal on "Guest Portal" wifi

I have wireless 1/2/3 set up working great. I would like to use the "Guest Portal" wifi as just another wireless SSID. However I cannot see any way to disable to captive portal option. There's no check box anywhere to disable it. I don't know if this is because my Orbi is in AP mode instead of router, but I would really like to have this 4th network without having to use a captive portal as it's incompatible with what I need. If this is not possible, could this be added as a feature request? Here's what my guest portal wifi page looks like, unless I'm missing something I don't see a way to disable captive portal.