Thanks for your quick reply, @Wayne-TP. I'm using an AmpliFi HD router with 3 mesh points. Interestingly, as of yesterday, I have regained full functionality of the Tapo light bulbs, via the Alexa...

@Wayne-TP I have the same problem as @DarrenAF. This started occurring a few weeks ago. 3 x Tapo L535 bulbs / HW Ver 3.0 / FW Ver 1.1.5 Build 240328 Rel. 194528 Bulbs cannot be controlled via Alexa...