@RodrigoBR 

Nice to see you again and I see you also commented on another post about Deco M9 plus firmware.

So far I didn't think the current issue might be related to 1.5.6 firmware.

Later if you are willing to update the firmware to 1.5.6 again(or maybe only update the main M9 plus), it would be highly appreciated if you could send feedback to support.forum@tp-link.com when the same performance issues started again.

At the same time, I will keep checking whether there would be more similar feedback.

Thank you very much for your cooperation and support.

Best regards.