@memox
Hi, may I know why you want to use WPS to connect to the guest network?
The "WPS" on Deco is more like a software button and so far it is used for the main network only.
I also checked the hardware WPS button on our Archer standard routers. It is also for the main network.
I think it is due to that Guest Network is not enabled by default, and most of the WPS features are designed for the main Wi-Fi network.
Thank you very much and best regards.