Router intermittently failing to authenticate wifi devices

Having a bit of an issue with my TP-LINK Archer C7 AC1750 router. I actually experienced this same issue with my Linksys e3000 router and went as far as replacing it because I could not figure out what was wrong and presumed it was a hardware issue.

The issue I am having is as follows:

We use apple products predominantly for Wifi (iPhone, iPad) in the home
We authenticate to the router, and everything works as expected upon initial setup
On random intervals, the router will boot off the wifi devices (wired network works fine).
Attempts to re-connect to the wifi network (the SSID is visible) are met with an "Authenticated failed" prompt.
The only solution to reconnect to the network is to reboot the router.

I am completely clueless as to why this is, as we are not changing the network credentials after they were initially setup, and the router is refusing to accept connections once the failure happens.

I am unclear what logs I could check, utilities I could run, settings I should verify, etc. I am a software developer by trade, so I'm not afraid to use the command line, but I'm just unsure where to start on how to resolve this.

Kyle B.

Posted 2016-07-20T13:56:21.740

Reputation: 295

Could you provide more details, such as the type of WiFi protection (WEP/WPA), the use you make of the WiFi router (WiFi AP, router, Ethernet switch, Internet box...), and if you spot any similarity between devices that have this problem (iOS version, specific app being used...)? Any detail will help people answer you. Thanks! – Nathan.Eilisha Shiraini – 2016-07-20T14:06:11.787

Could it be that there's another router hidden somewhere, with the same ESSID but different security settings? Many "Wi-Fi analyzer" apps would show this. – user1686 – 2016-07-20T14:09:41.477

Is the firmware for the device fully up-to-date? – Kaizerwolf – 2016-07-20T14:30:56.587

Hey guys - appreciate the prompt replies. I will update responses/post once I get home. – Kyle B. – 2016-07-20T15:19:52.903

Answers

In macOS (OS X) option-clicking on the Wi-Fi Menu Extra gives you the option to "Open Wireless Diagnostics…". It will bring up a diagnostic assistant that may be of help, but also be sure to check out the "Window" menu in that tool, which gives you access to several other diagnostic tools, including a convenient way to turn on a lot of logging and find the logs.

My hunch is that you're using WPA2 mixed mode (that is, WPA2 and WPA are both enabled), and that you're occasionally hitting spurious TKIP group cipher MIChael failures causing your network to, per spec, go down for 60 seconds. There are vanishingly few devices still in use that supported WPA but not WPA2, so it's best to set your wireless security to WPA2-only.

If your wireless router is in bridge mode (or if it doesn't connect to anything via its WAN port), then it may have actually crashed without you realizing it. Even with a crashed host OS on the router's CPU, the LAN-side hardware switch may keep running, and the wireless card may have enough firmware/microcode to stay visible in scans. Can you get to the router's web admin interface while clients are having this problem? If not, then it's probably crashed. If you were using your router as a gateway (including NAT service and DHCP service), as opposed to just a bridging AP, then you would have noticed that the router was crashed because NAT and DHCP would have failed.

Spiff

Posted 2016-07-20T13:56:21.740

Reputation: 84 656

Thank you for this. Do you feel there could be an issue by running both bands (5ghz and 2.4ghz) using the same WPA2 credentials? They have different SSID values. – Kyle B. – 2016-07-21T19:15:00.753

@KyleB. It's fine and even recommended (for user convenience) to use the same WPA2 passphrase on both bands. – Spiff – 2016-07-21T20:10:01.030