@spyfox 

Last thing to check would be to make sure your frimware is up to date.  If it is then likely the issue is that your 5GHz radio has gone bad. If that is the case and your router is still covered by the 2 year warranty there is a possiblity we will be able to replace it.  I would at that point contact our support line at 866-225-8139 so they can confrim troubleshooting and elgiblity.  

I did update the firmware as well so it is up to date. I purchased this from Amazon on 8/1/17...so it appears its still under warranty. I'll call the support line and check. 

Thank you very much for the reply...

Regards,

Mark

@spyfox 

Mark, 

Sounds good.  Please let us know if there are any issues with your dealing with our support team.

Did you delete my post from this forum about a similar issue?  Why?

@sojourn The region you registered under is New Zealand. This forum is for US customers so your thread was moved to our global support here:

https://community.tp-link.com/en/home/forum/topic/156491

@spyfox I blamed my ISP, changed my surge protector, updated all my drivers, cursed windows 10 but one thing when tried connecting my phone on 5ghz it still wasn't. I was already on a latest firmware so didn't had a clue. But just then in frustration I went back to the 1st factory firmware and rolled backed from all other latest firmware updates and guess it worked like a charm again.

P.S i have a archer ac1200 a6 router but this is a ongoing dilemma for mostly all new tplink routers. Perhaps it should work for you too. Best luck.