Hi, I saw that Thread but it is locked, I am facing almost same issue, After I "updated" my seperate router and accesspoint with tplink it has been started.

I am using air streaming feature between my smart TV and my Iphone, I can easly play videos from my mobile without any issue, also all smart phones at home which is connected to wireless work properly.

When I use Airplay future or stream future of Youtube same issue happens. It responses too slow, 5 seconds waits for example than my TV realize that connected device and start to playing then after while during the video plays if I want to pause from my phone when I press pause it responses like re-connect the tv and pause it or sometimes I check my phone while it locked youtube controller buttons dissaperad because the lost communication.

I tested my TV wired and wireless mode and tested with multiple smartphones and no result. I tried to disable different smart options but did not help, this is annoying, I don't know how can I solve...