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I have an ASUS RT-AC55U router purchased within the last 2 years that is experiencing continually more confounding problems.

Situation

More and more frequently, the following conditions suddenly present themselves:

  • My Windows computers, despite claiming an internet connection, are unable to connect to any web pages via 2.4G, 5G, or wired connections. Chrome gives the error DNS_PROBE_FINISHED_BAD_CONFIG.
  • On my Android devices, both the 2.4G and 5G connections become extremely slow. If I disconnect from either wireless network, I am unable to reconnect.
  • I am unable to access the router's internal settings page via wireless or wired connections, or access any other device on my local network.
  • If this happens while my work computer is connected to the wireless or wired networks and tunneled into the company's network via VPN, everything functions normally on my work computer. That is, I have no problems accessing web pages or the company's internal pages.

What I have tried

  • Unplugging and replugging the router (duh). This usually fixes the problem for a while.
  • Factory-resetting the router and rebuilding all settings from scratch. The only things I changed from the default were the network name and password and the router's login credentials. This reset didn't seem to have an effect on the timing or nature of the issue.
  • Making sure the router's firmware is up to date.
  • ASUS support. They told me to do the previous three things (duh). I'd prefer not to pursue their avenues further.
  • Unplugging the HDD from the router's USB 3.0 port. This doesn't seem to have an appreciable effect on the timing or severity of the issue.
  • Disconnecting all wireless and wired devices from the network then slowly adding them back one by one. No particular device seems to trigger the problem.

I am hard-pressed to think of anything that changed with my home network that specifically correlates with the onset of this problem. Any tips or tricks are appreciated, and I'm happy to provide more information if necessary.

Additional info

In response to comments, I've tried reconfiguring the DNS settings on the router and am now working on keeping it cooler. It's working right now, but I'm not holding my breath. It even stopped broadcasting the wifi signal entirely today, so I'm now fairly sure it's a hardware problem. I'll keep this up in case others find it useful, and I'll update it with changes to avoid something like this.

Update

ASUS warranty service sent me a refurbished RT-AC55U after diagnosing the problem. Can't complain about any aspect of the process except having to pay to ship the router to the repair center.

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  • Peter, what happens when you put a fan blowing on the vents of the router? This sounds like it's either overheating, or the beginning of some sort of component failure to me.
    – Tim_Stewart
    Commented Mar 13, 2018 at 19:07
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    The odd part is that you cannot access other devices in the network or the routers setup page, are you trying to access them directly via IP address or DNS name? If by IP address, I would suspect a hardware issue with the router like overheating. Otherwise, have you tried assigning the router's DNS servers manually to 8.8.8.8 and 208.67.222.222 (or other regional equivalents to Google or OpenDNS)? Can you ping the router, or 8.8.8.8 when this occurs?
    – acejavelin
    Commented Mar 13, 2018 at 19:11
  • @Tim_Stewart: I'll give that a shot. It's in a very well ventilated area (it's even sitting on a grated surface) and doesn't feel too warm, but it could be.
    – user746633
    Commented Mar 14, 2018 at 2:33
  • @acejavelin: Neither IP nor DNS works to access the router. Can't ping it or the DNS, no matter what settings. Slowly resigning myself to probably having to replace it or deal further with ASUS support.
    – user746633
    Commented Mar 14, 2018 at 2:34

3 Answers 3

Reset to default
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Your router is failing (physically)

I've seen the scenario you've described many times, particularly with consumer-grade networking gear. One moment it works, the next it's exhibiting unwanted behavior. Usually a reboot fixes things for a while, but eventually the reboots must happen too frequently to remain a viable solution.

Even solid-state technology can wear out (or worse, be of low-quality and fail prematurely). Someone else could provide detail on exactly what components in these devices are likely to fail and why, e.g. capacitors leaking fluid, but the fact stands that it does happen.

If you have access to another router, try temporarily putting it in your network. Even if not, if I were in your shoes I'd get a new unit (or make a warranty claim on the existing one).

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  • Pretty much my thoughts exactly. The only exception so far for me has been actiontec routers.
    – Tim_Stewart
    Commented Mar 14, 2018 at 5:21
  • This was my sinking feeling, but you never know when a weird combination of problems might be something easy you haven't thought of.
    – user746633
    Commented Mar 14, 2018 at 11:29
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I have got the dns server from my provider and specified it in the lan->dns server manually and it started to function properly however the wan->Connect to DNS Server automatically is set to yes because my provider doesn't allow to specify it manually. As well you can get provider's dns from the Network Map and then push on the Internet status and the necessary data will in on the right frame. As well you can try to specify google dns 8.8.8.8 in lan->dns server.

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  • There is not only Google on Internet, other public resolvers are 9.9.9.9, 1.1.1.1, etc.
    – Patrick Mevzek
    Commented Apr 15, 2018 at 21:14
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unreliability in my asus routers is caused by the nvram filling up, which causes a variety of random unpredictable errors from wifi disconnecting to losing port forward settings.

you can check free nvram from the nvram show command although you need to ssh or telnet into the router to run it.

When you buy the router there are several k of spare nvram, but mine quickly falls below 1k because I have a lot of clients connected and as well as settings which both use up a lot of the spare nvram. Resetting the router does recover nvram space, but doesn't last for long

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