@Pinky-12 

Hi, Thanks for the feedback.

I noticed you had both Apple devices. One particular reason for Apple devices is private address. Have you checked whether their MAC addresses have been changed when you are still able to access the internet?

https://support.apple.com/guide/iphone/use-a-private-network-address-iph6b324bb33/ios

It is also suggested to turn off "Private address" to see whether it helps.

As for the firmware you mentioned here-https://community.tp-link.com/en/home/forum/topic/619056?replyId=1347626, you are already on the latest firmware and there is no need to manually install any firmware yet. And the previous post-619056 is for HomeCare security system, it is not suitable for Deco XE75 Pro.

Thank you again and best regards.