No one can help?

I have the same issue, probably you want to follow this other thread https://community.tp-link.com/en/home/forum/topic/179162 there is more movement there, not great but at least some replies.

@fwinters 

Hi, there was a post here somewhere with a link to a beta firmware, I updated my P9s successfully to this beta and there are a lot more diagnosis and visibility of the method of connection also a web browser interface and monitoring of processor useage in each P9 etc.  Not sure the performance is any different but seems to be more stable.  However I think that in my case I have old wiring so the powerline not any faster than the wireless and I think that the units are not particularly long range in connecting to each other.  So I find that they still sometimes lose connection with each other and the signal is weak on some devices that are attaching from a room away.  I also found that it looks like the processor is at 100% utilisation frequently so maybe they are trying too hard to connect!  The one thing I would warn though is that there does not appear to be a downloadable current (original) firmware to take them back to factory config on the UK TP Link site.  Strangely it is there on the Spanish site but not sure the hardware is the same and last thing you need is an update to spanish language interfaces.  One other thing you could try is to use the instant chat function in the TP Link support site.  I did not have to wait long and the support assistant tried his best to help and diagnose issues.

@fwinters 

they are junk. I can't have the third P9 connected as it makes it too unstable. Random internet access failure, internet speeds vary all over the place and devices get dropped from app and the rediscovered at will. I am on the beta of the new firmware and it's done nothing to improve it. I'm basically complete fed up with them and sending them back. Absolute garbage, realeased way to early with very dodgy software. 

@Scoredo 

I tried the Ubiqiti Amplify HD games edition, comprises a cube shaped router and two mesh extenders.  works really well. great app and easy setup.  Really business grade kit and whole house covered.  Expensive but worth it.