RT-N66U loses internet connection - Troubleshooting tips

[PaulKemp]

Hi all,

Background:
The last few weeks I've been starting to have issues with the RT-N66U. The router has been performing impeccable for a few years, but has started acting up the last few weeks. I was on the Merlin FW but flashed the original back when I started troubleshooting. I'm on FW 3.0.0.4.376_1071 currently.

Problem:
I loose internet connection on my clients. Wifi is good, I'm able to log into the router, but I cant reach the web. I try to ping from the router, but no response.

Fix:
I login and reboot the router. This always works. It comes back up and works flawless.

I need some tips on what I can do to troubleshoot this. Where to start etc. The only thing I've done besides flashing the fw is setting the DNS. Any help greatly appreciated.

 

[jlake]

Troubleshooting steps

http://forums.smallnetbuilder.com/showthread.php?t=12453

 

[PaulKemp]

I was thinking more in the lines of decoding the error logs. Factory resetting the router is out of the question with dhcp reservations, port forwarding, vpn, ddns and all the other stuff I've done to customize the router up through the years.

 

[RMerlin]

Look for any WAN-related entries in Syslog for starter.

 

[PaulKemp]

Look for any WAN-related entries in Syslog for starter.

Atleast I've got this, if this is not a common error, this might be the culprit:

"Jul 13 19:31:48 WAN Connection: ISP's DHCP did not function properly."

 

[RMerlin]

Atleast I've got this, if this is not a common error, this might be the culprit:

"Jul 13 19:31:48 WAN Connection: ISP's DHCP did not function properly."

This is a very generic error message that could mean anything unfortunately.

Look for any mention that eth0 link went down then up. Those indicate that your modem has crashed and rebooted.

 

[richardeid]

I've also been seeing this same issue, though I'm using an RT-N16. I'm guessing the N66 has more verbose logging because I don't see the same error the OP is seeing anywhere in my syslog. In fact, I don't see any error. DNS just stops working on all the client machines connected.

One thing I've noticed is that while I can't ping, say, www.google.com from any of my clients I can indeed ping www.google.com from the router's BusyBox CLI. So it's like DNS isn't entirely dead, but the router gets to a point where it is no longer resolving for clients. If I ping a DNS name from the router and use the IP it resolves to in a web browser the pages load just fine. Everything else also seems to work fine on the router when DNS dies.

Rebooting the router solves the issue every time.

Is there a more verbose log I can find? dmesg doesn't show anything and the remote logging server I'm using shows pretty much the same stuff as dmesg.

FWIW, I'm on stock ASUS 5517. I believe it is with this firmware that the problem began.

Being that I'm using a different router, should I start my own thread? I don't mean to hijack this thread, but it looks like we're having the same issue, though on two different routers and firmwares. I've also noticed a few other posts around here where people are reporting the same/similar issues.

I've tried reflashing 5517 and also doing a factory reset and setting everything up from scratch (not from a settings backup) and I'm still seeing the issue.

If I can provide any more info that might help I'll be happy to but I don't know where else to turn at this point.

 

[PaulKemp]

Being that I'm using a different router, should I start my own thread? I don't mean to hijack this thread, but it looks like we're having the same issue, though on two different routers and firmwares. I've also noticed a few other posts around here where people are reporting the same/similar issues.

HI! In my eyes there is no need for starting a new thread. At this point neither of us knows what exactly what the culprit is. I'll take your notes and look into this when I come home. Very strange, the router has been performing very good for two years, now all of a sudden, my clients loose internet once a day. Strange times friends, strange times.

 

[MilkManX]

NTFS (with native replay) support included
Dec 31 17:00:08 kernel: optimized: speed
Dec 31 17:00:08 kernel: Build_for__asus_n66u_2011-10-27_U86_r187446_b122
Dec 31 17:00:10 stop_nat_rules: apply the redirect_rules!
Dec 31 17:00:10 WAN Connection: Ethernet link down.
Dec 31 17:00:10 kernel: scsi 0:0:0:0: Direct-Access Multi Flash Reader 1.00 PQ: 0 ANSI: 0
Dec 31 17:00:10 kernel: sd 0:0:0:0: [sda] Attached SCSI removable disk
Dec 31 17:00:10 kernel: sd 0:0:0:0: Attached scsi generic sg0 type 0
Dec 31 17:00:14 dnsmasq[368]: warning: interface ppp1* does not currently exist
Dec 31 17:00:14 RT-N66R: start httpd
Dec 31 17:00:14 syslog: Generating SSL certificate...
Dec 31 17:00:15 disk monitor: be idle
Dec 31 17:00:16 miniupnpd[401]: HTTP listening on port 59791
Dec 31 17:00:16 miniupnpd[401]: Listening for NAT-PMP traffic on port 5351
Dec 31 17:00:22 start_nat_rules: apply the nat_rules(/tmp/nat_rules_eth0_eth0)!
Dec 31 17:00:23 kernel: nf_conntrack_rtsp v0.6.21 loading
Dec 31 17:00:23 kernel: nf_nat_rtsp v0.6.21 loading
Dec 31 17:00:23 rc_service: udhcpc 419:notify_rc stop_upnp
Dec 31 17:00:23 miniupnpd[401]: received signal 15, good-bye
Dec 31 17:00:23 rc_service: udhcpc 419:notify_rc start_upnp
Dec 31 17:00:23 miniupnpd[468]: HTTP listening on port 38802
Dec 31 17:00:23 miniupnpd[468]: Listening for NAT-PMP traffic on port 5351
Dec 31 17:00:24 WAN Connection: WAN was restored.
Dec 31 17:00:26 ntp: start NTP update
Jan 20 17:45:31 rc_service: ntp 467:notify_rc restart_upnp
Jan 20 17:45:31 rc_service: ntp 467:notify_rc restart_diskmon
Jan 20 17:45:31 rc_service: waitting "restart_upnp" via ntp ...
Jan 20 17:45:31 miniupnpd[468]: received signal 15, good-bye
Jan 20 17:45:31 miniupnpd[476]: HTTP listening on port 37682
Jan 20 17:45:31 miniupnpd[476]: Listening for NAT-PMP traffic on port 5351
Jan 20 17:45:32 dhcp client: bound 24.255.18.84 via 24.255.18.1 during 86400 seconds.
Jan 20 17:45:32 disk monitor: be idle
Jan 20 17:46:06 crond[372]: time disparity of 2132685 minutes detected

I have this router and it has worked great for months-Bought Sep 9th 2014.
Had a major slow down/disco with it Sunday afternoon. I then did a full restart of the Modem and Router and did the NVRAM reset on the router. At that point I updated the FW to the latest ASUS one. Using Cat5e cable from Modem to N66U.

Using a Motorola SB 6120 Modem that I have had for probably 3+ years. Thinking this may be the issue but with lots of folks having issues with the RT-N66U I thought I would check to see if there is anything else. I don't use DDNS or any VPN. It is just used for internet(web,netflix,ect.) and Xbox. No special routing or anything.

Any ideas?

I don't want to buy a new modem or have to RMA this router if I don't have to.

 

[ca509]

It is the same for me: AC68U behind a ADSL modem. If the connection is dropped the router is unable to reconnect. The modem stays sync all the time. A restart of the router, not the modem, helps and everything is back to normal.

Seems to apply to people using external dial-up modems.
I believe it was introduced with firmware 376.xxxx and above. I flashed back t 374.5656 and everything is fine again, the router reconnects after the connecction is lost.

Might by something with their new AiProtection stuff..

My log was like

Jan 17 20:27:12 WAN Connection: Fail to connect with some issues.
Jan 17 20:27:12 dnsmasq[1363]: warning: interface tun21 does not currently exist
Jan 17 20:27:12 dnsmasq[1363]: warning: interface ppp1* does not currently exist
Jan 17 20:27:12 start_nat_rules: apply the nat_rules(/tmp/nat_rules__eth0)!
Jan 17 20:27:12 pptp[1380]: pppd 2.4.7 started by admin, uid 0
Jan 17 20:27:13 pptp[1380]: Connect: ppp0 <--> pptp (10.0.0.138)
Jan 17 20:27:17 RT-AC68U: start httpd - SSL
Jan 17 20:27:43 pptp[1380]: LCP: timeout sending Config-Requests
Jan 17 20:27:43 pptp[1380]: Connection terminated.
Jan 17 20:27:43 pptp[1380]: Modem hangup
Jan 17 20:27:54 pptp[1380]: Connect: ppp0 <--> pptp (10.0.0.138)
Jan 17 20:28:24 pptp[1380]: LCP: timeout sending Config-Requests
Jan 17 20:28:24 pptp[1380]: Connection terminated.
Jan 17 20:28:24 pptp[1380]: Modem hangup

 

[MilkManX]

Anyone have this issue on ASUS firmware and then try MERLIN and it works again?

 

[MilkManX]

I went ahead and installed the latest Merlin last night. Will report if this fixes the issue. Already I like how snappy it is compared to the latest ASUS firmware.