To supplement the message I sent earlier, I contacted TP-Link's email support with this question. However, I received a reply that "Our product cannot use the guest network function in AP mode." I'm...

English is not my native language (I can speak Japanese only.), so it is may be difficult to understand by my explain. <Topology> ONU ---- Router ---- HUB#1 ---- Deco#1(AP mode) ---- HUB#2 ----...