WRT1900AC Spontaneous Reboots, lockups

[sfx2000]

In my old Netgear router and Zyxel routers, there were DNS entries in the WAN (Internet) section AND the LAN/DHCP section.

If you hard set the WAN/Internet DNS entries, the router itself would use those addresses to do lookups.

If you left the LAN/DHCP settings alone, the router would act as a proxy and forward DNS queries to whatever DNS entries appeared in the WAN section. If you hard set the LAN/DHCP settings to another DNS server however, the router would assign those servers to the clients via DHCP and bypass the router DNS proxy.

I understand what the router is doing and I understand why. However, it's still a very counterintuitive place to put those settings. If those DNS entries are designed to be used by the router and all client lookups are supposed to be proxies, those DNS entries should not be in the local connectivity page. It would make more sense to put them in the Internet page, just like pretty much every other router I've ever used.

UI/UX is always a challenge - Linksys' implementation is counter-intuitive if one has seen other implementations, but if not, then it's pretty easy... other OEM's have more granular configuration options (e.g. Netgear/Zyxel as an example), other OEM's for SOHO routers have a single option.

sfx

 

[chadster766]

Happen on both adapters?

One is Realtek based (the 180), the other is Atheros (the 552)... in kernel drivers, or via wireless-compat or direct download/build the modules directly?

Just trying to rule out the client side...

sfx

Adapters are using kernel drivers. It's nice that they work straight out of the box.

 

[sfx2000]

Adapters are using kernel drivers. It's nice that they work straight out of the box.

Doesn't mean they work well however

Both cards - see the same results? Mostly interesting in the associate/deassociate sequence of events...

If it happens with both STA's, then time to zero in on the Marvell driver on the WRT...

sfx

 

[sfx2000]

Even if it were - and I'm also convinced it isn't - a web browser should never be able to cause a device to kernel panic. At best it's a serious bug. At worse it's a security issue - hellooooo DoS.

This is probably just a case of first level tech support with no technical knowledge and just a few scripted troubleshooting steps being applied to the customer's request.

TLDR - disable Guest Access on the WRT1900ac, probably also applies to any other SmartWIFI enabled device from Linksys...

@rmerlin - you're one of the few that might understand the implications of a buggy WebGUI...

The WRT1900ac Guest Network - it's an Open 802.11 WiFi with a captive portal... using dnsmasq to re-route UDP-53 queries to the portal. The fact that the WRT webserver is in the middle - for a haxxor, it's like "being there"... Note that the 802.11 side is open without WPA/WPA2, this makes it even easier to start hacking the WPA/WPA2 handshakes on the same AP.

The Guest Network Captive Portal uses the same WebServer daemon as the WebGUI for config...

For Linksys SmartWIFI - this is one of those things, not so very smart...

scary eh?

sfx

Might also want to ensure that configure via WAN is also disabled... but this is general guidance for any SOHO router...

 

[htismaqe]

They tried to offer me hardware replacement. I refused and told them it appears to be a software issue. They've escalated it to Tier 2, we'll see what they say when they call.

 

[sfx2000]

They tried to offer me hardware replacement. I refused and told them it appears to be a software issue. They've escalated it to Tier 2, we'll see what they say when they call.

Yep - for Tier 1 - replace the HW if they can't make it through the scripts...

These problems are SW related - the HW is good for the most part - I can see one-offs, but the issues here are common, so it has to be SW...

sfx

 

[chadster766]

Well I finally finished making a router stress testing platform.

I tried to recreate the "Kernel Panic" reboot that I captured from the serial console.

I wrote a script that loops through commands below 100 times:

1. Connect adapter1 to the WRT Wireless
2. Run iPerf throughput test
3. Disconnect adapter1
4. Connect adapter2 to the WRT Wireless
5. Run iPerf throughput test
6. Disconnect adapter2

I ran this twice consecutively. Once with adapter's set static ip's and once DHCP release and renews.

Approx 20gig throughput not a single failure

Any suggestions on addition testing? I'm thinking put the router's 2.4 ghz in mixed mode and have the adapters change protocols each time they connect.

What are your thoughts on whether or not this is a hardware interrupt conflict in the router's hardware config?

How can hardware interrupts be changed in U-Boot?

I ran this test again but increased the loop count to 400. It took 6 hours to complete.

Throughput iPerf testing is WLAN to LAN.

It completed without reboots

Files attached (PDF works best for me):

1. Serial output during test
2. Testing script output
3. Sysinfo.cgi after test

 

[sfx2000]

I ran this test again but increased the loop count to 400. It took 6 hours to complete.

Throughput iPerf testing is WLAN to LAN.

It completed without reboots

Files attached (PDF works best for me):

1. Serial output during test
2. Testing script output
3. Sysinfo.cgi after test

Hokay... I'm going to back away from things...

I had the WRT1900ac boxed up to send over to a family member (my 70 year old mother) who actually has a "typical" mixed mode/mixed purpose network...

Gotta love Mom - she's fairly progressive

Anyways - breaking the unit out of the box and putting it back online in my LAN... mostly due to issues observed on this thread.

1) WebGUI and OpenDNS/GoogleDNS - entering the values, it's going to reboot, and DHCP clients will indicate AP-Local address for the DNS server - not an issue, did a quick PCAP as the WRT is subnetted, so I did a CAP on the WAN side of the WRT - it follows the settings

2) Static DHCP reservations on WebGUI - it will reboot on every action here - not a bug

3) cannot reproduce Chad's reboot issue - I'm a bit more limited on clients - MacBook Air 2014 802.11ac and an Asus USB-56AC with current drivers on Win7 (latest driver actually enables 256-QAM).

the 2.4GHz Turbo-QAM enhancement, probably more of a step back on the Asus dongle - but perhaps another topic here...

So for debug purposes - put the device back into factory mode - reset via...

http://linksyssmartwifi.com/

Go to Troubleshooting, Diagnostics, and reset the device to factory settings... once up after the reboot - disconnect power - and hit the reset button on the back for a few seconds, and power it back up...

Current FW that I'm working with - 1.1.7.160582

So I'll let it soak on my network for a couple of days to see what's up before I put it back in the box to send over to Mom...

(FWIW - it's a good performer, between it and my Airport Extreme's - about the same, and I wouldn't expect a netgear or asus box to be any better)

sfx

 

[sm00thpapa]

I now have 30 devices connected to my WRT1900AC and it works flawless. No issues what so ever. So the rebooting is router specific. May be your modems and not the router.

 

[G997]

I now have 30 devices connected to my WRT1900AC and it works flawless. No issues what so ever. So the rebooting is router specific. May be your modems and not the router.

+1
The WRT1900 is very soild

 

[htismaqe]

I now have 30 devices connected to my WRT1900AC and it works flawless. No issues what so ever. So the rebooting is router specific. May be your modems and not the router.

I don't have a modem. I have ethernet over fiber. Also, I've had two and they both do the same thing.

 

[htismaqe]

1) WebGUI and OpenDNS/GoogleDNS - entering the values, it's going to reboot, and DHCP clients will indicate AP-Local address for the DNS server - not an issue, did a quick PCAP as the WRT is subnetted, so I did a CAP on the WAN side of the WRT - it follows the settings

2) Static DHCP reservations on WebGUI - it will reboot on every action here - not a bug

It doesn't reboot every time. Normally, it does a "soft" reset when you change any of the local LAN settings, I'm assuming so that clients will renew and get updated DHCP information. This soft reset appears to be just a quick restart of the wireless radios and last about 5 seconds. It's not disruptive really at all.

Of course, there are times when it does reboot, which is a complete power cycle/restart and last about 30 seconds. It can be much more disruptive.

I've come to these conclusions by watching the sysinfo.cgi.

 

[speedingcheetah]

When I was testing mine, if I disconnected it from my WAN as the main router, then later I fired it up and connected it up to my current router.(WAN would be DHCP)..just to check for updates or to play with it some more.... The WRT auto changed its Static IP address I had set for it from a 192.168.X.X to a 10. something....AND it erased all my static DHCP reservations. Pretty much the only settings that did not change were the wifi settings. No other router I have used would do this. If I set settings, I expect them to stay, I don't have the time to go in a reset everything again, and with Linksys horrible UI, it takes forever compared to my Asus router.

I have yet to see it at my local Microcenter(where I work at). Best Buy is the only store that sells it around here.

 

[chadster766]

When I was testing mine, if I disconnected it from my WAN as the main router, then later I fired it up and connected it up to my current router.(WAN would be DHCP)..just to check for updates or to play with it some more.... The WRT auto changed its Static IP address I had set for it from a 192.168.X.X to a 10. something....AND it erased all my static DHCP reservations. Pretty much the only settings that did not change were the wifi settings. No other router I have used would do this. If I set settings, I expect them to stay, I don't have the time to go in a reset everything again, and with Linksys horrible UI, it takes forever compared to my Asus router.

I have yet to see it at my local Microcenter(where I work at). Best Buy is the only store that sells it around here.

When a Linksys Smart WiFi detects what it thinks is an IP Conflict it will automatically change to fix the conflict.

Examples of a typical conflict would be:

• An IP Address in the 192.168.1.x range is given to the Linksys router WAN
• There is another device with the same IP as the Linksys router on the network

Personally I would rather it didn't but it helps the novice users.

 

[htismaqe]

The WRT auto changed its Static IP address I had set for it from a 192.168.X.X to a 10. something

The Netgear R7000 does this too IIRC.

AND it erased all my static DHCP reservations. Pretty much the only settings that did not change were the wifi settings. No other router I have used would do this.

If you change the LAN address of the router, your DHCP reservations are no longer valid. You're going to have to either edit them or change your IP address back to match them. Again, this happens with the Netgear R7000.

If I set settings, I expect them to stay, I don't have the time to go in a reset everything again, and with Linksys horrible UI, it takes forever compared to my Asus router.

The Asus is only faster with DHCP reservations because you can SSH into the router and load the entire reservation table via a shell script (which doesn't suit every user). It's definitely not faster doing it via the GUI.

 

[speedingcheetah]

When a Linksys Smart WiFi detects what it thinks is an IP Conflict it will automatically change to fix the conflict.

Examples of a typical conflict would be:

• An IP Address in the 192.168.1.x range is given to the Linksys router WAN
• There is another device with the same IP as the Linksys router on the network

Personally I would rather it didn't but it helps the novice users.

There was no ip conflict.

Everything thing on my network is set on the 192.168.0.X subnet.

I can connect other routers to my main router or switch, and they do not change their set ip address or set static DHCP reservations..no matter if they are set to the same 192.168.0 range...or another, like 192.168.1.x....or 10.0.X.X.

You say its an auto function. I do not like this. I suggest they make an option to disable this feature should the user wish to.

 

[speedingcheetah]

The Netgear R7000 does this too IIRC.



If you change the LAN address of the router, your DHCP reservations are no longer valid. You're going to have to either edit them or change your IP address back to match them. Again, this happens with the Netgear R7000.



The Asus is only faster with DHCP reservations because you can SSH into the router and load the entire reservation table via a shell script (which doesn't suit every user). It's definitely not faster doing it via the GUI.

I changed the routers ip address to what I wanted, then added my DCHP reservations. Only when I connected it to my other router, did it reset everything automatically. I do not have any other routers that do this. I just hooked up a Cisco e2000 set to 192.168.1.1 and has other DCHP reservation set for my parents house...and it works fine getting the WAN DHCP info from my router, though anything connected to the Cisco is is the 1.1 subnet.

The Asus UI is much faster to add DHCP reservations to than the Linksys UI. I just copy and paste the MAC address and IP address from a text file in to the 2 fields...click +, done. Linksys, I don't recall the exact process, but I do remember it being much more annoying.

 

[sm00thpapa]

I don't have a modem. I have ethernet over fiber. Also, I've had two and they both do the same thing.

Well check your Ethernet over fiber. I'm on my first router with no issues in 2 months. So it's not the router or firmware.

 

[htismaqe]

The Asus UI is much faster to add DHCP reservations to than the Linksys UI. I just copy and paste the MAC address and IP address from a text file in to the 2 fields...click +, done. Linksys, I don't recall the exact process, but I do remember it being much more annoying.

Adding DHCP reservations in the Linksys is the exact same process. Copying and pasting from a text file works as well and takes the exact same amount of time.

The only GUI that is significantly slower is Netgear because you actually have to enter a 2nd screen to input the individual reservations.

 

[htismaqe]

Well check your Ethernet over fiber. I'm on my first router with no issues in 2 months. So it's not the router or firmware.

I have tried multiple routers. My ISP connection is not the issue. It's been installed for over 2 years and I previously had a Netgear WNDR3700 with over a year of continuous uptime.

I'm currently at 41 hours of uptime. It absolutely IS a firmware issue related to GUI management and this was verified by Linksys support last night on the phone. I am expecting a call from Engineering today.