I have a brand new Asus RT-AC5300 that I'm trying to setup in our office in access point only mode. It works ok, but after about 15 min some of the clients stop connecting. It's mostly mobile phones that have these issues, my laptop is ok.

I've upgraded the firmware to the latest version, I've tried the Merlin firmware, it works fine at the beginning then it just stops working. Most of people in the office are on iPhones and it's particularly annoying on those as I believe they turn off the WiFi when they go to sleep mode and then they fail to connect to the WiFi.

I've also tried to turn off Smart Connect and all the other features under the Professional tab. Still the issue is there after a few minutes. A reboot of the router also allows devices to connect again, but after a white it stops working.

I've tried to setup separate 2.4 and 5 GHz network SSIDs. My Android phone will work ok on the 5 GHz but is always stuck on Obtaining IP address on the 2.4 GHz. My old laptop that only has 2.4 GHz works fine even if I disconnect it and connect it again a few times. iPhones initially connect to the 5 GHz, but then they fail to connect to it.

I really don't understand what is going on, I've been using Asus devices for a long time and never had issues. Does anyone have an idea?

I've set it in Router mode now and turned off DHCP and will see if that changes anything next time I'm in the office.