RT-AC68U losing LAN connection (ethernet)

[liquefry]

I'm having some trouble with my month-old RT-AC68U. Every so often (particularly noticeable when gaming) actively connected devices seem to get dropped by the router for a few seconds. Enough to get kicked from gaming servers but not super noticeable when browsing web, unless you happen to be loading a page when it happens.

My setup is:
WAN -> TP-LINK 8960N (bridged mode, IP 192.168.2.1) -> RT-AC68U (IP 192.168.1.254) -> LAN (wired / wireless, IP range 192.168.1.x).

The TP-Link modem log is showing solid synchronisation with my ISP and no errors, so there does not appear to be any problem at that end. It's also on full bridge mode, so no DHCP/NAT/anything running, just passing through PPPoE signals to the Asus router.

I'm running 3.0.0.4.374.39 (Merlin build), problem exists with both Merlin and ASUS-wrt firmwares.

My system log in the asus shows lines of:
Apr 4 11:27:23 dnsmasq-dhcp[22311]: DHCPINFORM(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:27:23 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:28:46 dnsmasq-dhcp[22311]: DHCPINFORM(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:28:46 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:29:59 dnsmasq-dhcp[22311]: DHCPREQUEST(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:29:59 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:30:02 dnsmasq-dhcp[22311]: DHCPINFORM(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:30:02 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:31:17 dnsmasq-dhcp[22311]: DHCPREQUEST(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:31:17 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:31:21 dnsmasq-dhcp[22311]: DHCPINFORM(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:31:21 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:32:00 dnsmasq-dhcp[22311]: DHCPREQUEST(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:32:00 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox
Apr 4 11:32:03 dnsmasq-dhcp[22311]: DHCPINFORM(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx
Apr 4 11:32:03 dnsmasq-dhcp[22311]: DHCPACK(br0) 192.168.1.47 xx:xx:xx:xx:xx:xx blackbox

(the xx lines replacing the actual number for my PC). Blackbox/192.168.1.47 is the ethernet connected PC. The times listed coincide with the LAN being lost on that PC for a few seconds. These messages are not entirely for that machine, but predominantly - it looks like they only happen for machines that are actively using the internet at the time.

Other settings:
QoS is on (seems to happen without it as well but I havent checked), default settings with added line for VOIP machine. There is no traffic to the VOIP at the time of disconnection.
Wireless: 2.4GHz (20/40MHz) and 5GHz (20/40/80 MHz) enabled, different SSIDs
Other settings: UPnP is disabled, NAT enabled, MTU is 1492, enable VPN+DHCP is set to yes, IPv6 is disabled, I have a VPN set up but doesnt seem to make a difference either way, firewall enabled on default settings. No USB disk, AI cloud, guest network or parental controls.

I've tried quite a few things to figure out what's going on, rebooting, different subnets, etc etc, but am at the end of my knowledge and not turning up any threads in google that have anything I havent already tried. It is interesting that the log shows DHCP for the PC that loses connection every time it does so, but I'm not sure if that is cause or effect. Any help greatly appreciated!

 

[KGB7]

What is DHCP Query Frequency set to??

Also manually set channels for WiFi.

 

[liquefry]

What is DHCP Query Frequency set to??

The lease time is 86400 - is that the same as query frequency? I havent changed anything from default on that apart from static assignments of particular IPs.

Also manually set channels for WiFi.

OK, have done that, and reduced 2.4GHz bands to 20MHz. Note my problem is for wired connections.

 

[liquefry]

What is DHCP Query Frequency set to??.

Just googled this - the option to change query frequencies does not appear for pppoe connections.

 

[liquefry]

Some other things I've just tried - will report back on impact:
- turned off QoS
- turned off NAT acceleration
- turned off the "enable VPN and DHCP connection" option, no idea what that does.

 

[KGB7]

Forgot you ppoe guys don't need that option, but its in wan options.

QoS off.
Nat acceleration on.

Since the issue is with all firmwares;
Try a different cable.
Also for your lan card in your PC, turn off power management and update drivers.

 

[liquefry]

Try a different cable.

Not sure if you mean between router and PC, or router and modem? Have changed the one to the PC, according to the logs I'm still getting DHCP requests so assume it is still happening (not able to game to check for dropouts at the moment, and it is momentary enough that it is not really noticeable when browsing).

Also for your lan card in your PC, turn off power management and update drivers.

Check on the power management, on Asus website (it's an ASUS mobo with integrated network adaptor) there is only one driver which I already have installed.

I dont think it is just the PC that this happens on - may be wireless and wired. From recent logs you can see it is affecting other devices - two of the three below are wirelessly connected.

Apr  4 17:13:38 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.53 84:7a:--:--:--:-- 
Apr  4 17:13:38 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.53 84:7a:--:--:--:--  android
Apr  4 17:14:53 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.47 bc:ae:--:--:--:--
Apr  4 17:14:53 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:14:57 dnsmasq-dhcp[1905]: DHCPINFORM(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:14:57 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:25 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:20:25 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.59 dc:3a:--:--:--:-- 
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.59 dc:3a:--:--:--:-- NP-1GS3CN047844
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPINFORM(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:49 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.59 dc:3a:--:--:--:-- 
Apr  4 17:20:49 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.59 dc:3a:--:--:--:-- NP-1GS3CN047844

Just a thought - could this be temperature related? It is not hot here at all today, but am wondering... all the devices affected are actively transferring data - perhaps this device is getting too hot under load? log shows:
2.4 GHz: 53°C - 5 GHz: 56°C - CPU: 87°C

I've moved it to sit by itself with plenty of ventilation all round to see if that makes a difference too.

 

[RMerlin]

Not sure if you mean between router and PC, or router and modem? Have changed the one to the PC, according to the logs I'm still getting DHCP requests so assume it is still happening (not able to game to check for dropouts at the moment, and it is momentary enough that it is not really noticeable when browsing).



Check on the power management, on Asus website (it's an ASUS mobo with integrated network adaptor) there is only one driver which I already have installed.

I dont think it is just the PC that this happens on - may be wireless and wired. From recent logs you can see it is affecting other devices - two of the three below are wirelessly connected.

Apr  4 17:13:38 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.53 84:7a:--:--:--:-- 
Apr  4 17:13:38 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.53 84:7a:--:--:--:--  android
Apr  4 17:14:53 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.47 bc:ae:--:--:--:--
Apr  4 17:14:53 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:14:57 dnsmasq-dhcp[1905]: DHCPINFORM(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:14:57 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:25 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:20:25 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.59 dc:3a:--:--:--:-- 
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.59 dc:3a:--:--:--:-- NP-1GS3CN047844
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPINFORM(br0) 192.168.1.47 bc:ae:--:--:--:-- 
Apr  4 17:20:28 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.47 bc:ae:--:--:--:-- blackbox
Apr  4 17:20:49 dnsmasq-dhcp[1905]: DHCPREQUEST(br0) 192.168.1.59 dc:3a:--:--:--:-- 
Apr  4 17:20:49 dnsmasq-dhcp[1905]: DHCPACK(br0) 192.168.1.59 dc:3a:--:--:--:-- NP-1GS3CN047844

Just a thought - could this be temperature related? It is not hot here at all today, but am wondering... all the devices affected are actively transferring data - perhaps this device is getting too hot under load? log shows:
2.4 GHz: 53°C - 5 GHz: 56°C - CPU: 87°C

I've moved it to sit by itself with plenty of ventilation all round to see if that makes a difference too.

The DHCP requests are sent by that dc:3a: device. This has nothing to do with the router, look for the problem on that device's end. It's the one generating the requests, and the router is simply answering them.

 

[KGB7]

I get dhcp queries all day from all devices connected to the router and have no issues. There was an option in past firmwares to turn off the logs query but now its gone.

Disconnect all devices from router except for gaming PC and see if you still have issues. Turn off WiFi for both bands on the router just to make sure nothing connects to it.

The lan card is not made by Asus, could be made by Intel, relteck or some other brand. So get the latest driver directly from lan card maker.

Do you still have same issue if gaming PC is connected directly in to the modem?
If you do, then power down the modem for about half hour. If the issue is gone then issue might be or was with the modem or your ISP.
If the issue comes back while connected directly in to modem then time to get a new modem or call your ISP.

 

[liquefry]

I get dhcp queries all day from all devices connected to the router and have no issues. There was an option in past firmwares to turn off the logs query but now its gone.

You can still turn it off, its the second option on the DHCP page.

The lan card is not made by Asus, could be made by Intel, relteck or some other brand. So get the latest driver directly from lan card maker.

I updated the driver (it was a realtek one) and it may be fixed - I have not been interrupted in 3 hours of gaming anyway. The log is still full of DHCP queries but they didnt seem to interrupt the gameplay - and this time they are "DHCP inform" rather than "DHCP request".

Anyway if I get the problem again I'll isolate the gaming PC on the modem direct and see what happens, will report back if I do have further problems. Thanks for your help (and Merlin)

 

[seamanrob]

I signed up specifically to let you know that we had similiar issues with our LAN connection, both ethernet and wireless. We tried changing firmware to Merlin, DDWRT etc, nothing helped.
Out of desperation, I changed the DCHP pool address from 192.168.0.1 to 1.1 and things began to improve. I narrowed the issue down to a "smart" network hub that had addressed itself as 192.168.0.1 on the network, static. So there was an IP conflict. Since that time, we have had almost instantaneous connections and no further issues. It was especially noticeable on windows 10 devices. For some reason, android was more forgiving of this conflict.

If you are having these difficulties, I would recommend rechecking all assigned IP addresses on the actual hardware, ie, not at the router admin page.

Good luck!