For others with this issue:  Try not using the 2nd 5ghz radio.   My network devices (43 of them) seem to be stable so far.  Just trying to isolate the problem.

Thanks ITguyDJ, this did not work for me. I have tried all radios off, 1 on, no security, etc. Nothing. 

Bummer sentryknight,   Thanks for testing my theory.   I'm out of ideas. Hope that TPLink engineers can figure it out.

Carl,  I posted earlier about experiencing this spotty disconnect issue on my new C4000 router and have experimented with several things trying to isolate the problem.   After reading some of the knowledge base articles about interference from other networks and devices, I decided to change the channel # and bandwidth to a manual setting.   I changed the second 5ghz radio to 20 mhz bandwidth and channel 149.    Also took the security settings off of auto and set to WPA2-PSK and AES.    I left the 2.4ghz and first 5ghz radio at the default auto settings.  I've now been totally stable for 4 days with 43 various devices connected including iphones, ipads, Windows laptops, Chrome Laptops, and numerous tp-link and google smart home devices.    I'm sure network environments and potential interference items vary but this is working for me. Thanks for your articles in the knowledge base and support in this user forum!

I am still having the issue with iPhones not connecting. Is it possible because I used special charachters like % and & in the passwords that something got confused along the way?

My router developed this problem today.  Was running fine for about 2-3 weeks, then suddenly no 2.4 ghz can connect.  Tried all suggested work-arounds, get "incorrect password" or I get "could no join network"

Really sucks because most my home automation is 2.4 ghz and don't support 5 ghz.

I've notices that the A20 firmware is 7+ months newer than the C4000, for essentially the identical hardware.  

Anyone try flashing the A20 firmware over the C4000?

Are we going to get updates on this issue?

I posted this earlier, but my devices, both 2.4 and 5 ghz have been rock solid since changing the channels to less congested frequency's.   I used a utility to monitor the relative strength and channels used by neighbors and set my c4000 to use less congested channels.    I have a smart home with over 43 devices of all types and everything has worked great for weeks.  Others may be having a different problem but all my systems are running great with the C4000.

ITguyDJ wrote

I posted this earlier, but my devices, both 2.4 and 5 ghz have been rock solid since changing the channels to less congested frequency's.   I used a utility to monitor the relative strength and channels used by neighbors and set my c4000 to use less congested channels.    I have a smart home with over 43 devices of all types and everything has worked great for weeks.  Others may be having a different problem but all my systems are running great with the C4000.

 

I ran a wifi analyzer to pick the best channels manually, no dice.  Even if there was significant congestion, I'm inches from the device and it won't connect.

Carl wrote

Hi everyone,  

 

 

 

Thank you for letting us know that this is not just isolated to one user.  Because of this I have forwarded this thread and the content in it to our system enigneering team.  Once i have a followup i will let all of you know.

 

Best Regards 

So... what's the scoop, Carl?