@Solla-topee thank you for your suggestions. I ended up switching my router to the Orbi Pro 6 and all swtiches/plugs are back working. Looks like the issue was with Asus latest firmware update.

@Hippo It's an Asus router issue with their latest firmware upgrade. I switched to Orbi Pro 6 and issue resolved.

I've had TP-Link smart switches and plugs for the last 5 years and never had an issue. I recently updated the firmware on my router (Asus GT-AX11000) and updated my iPhone's IOS to 15 and nothing but...