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Topic: TP-Link wr841n v8 - WAN connection drops after some time

The content of this topic has been archived on 26 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.

I have the latest Barrier Breaker version of OpenWRT installed. After the router is started, the internet is accessible for a few minutes and after that the WAN connection just drops. But, during this time the LAN still works properly.

The only way to get the internet connection back is to either reconnect the WLAN interface in the OpenWRT web portal or to restart the router. Checking `dmesg` output before and after the connection drop resulted in no extra information.

I faced the exact same problem with Attitude Adjustment also. Here is the forum post concerning that problem.

Any ideas on how to solve this problem?

Note: I did a 30/30/30 Hard reset just before and just after installing OpenWRT.


I'm having similar problems with tp-link wdr3600. I have to restart my WAN connection, because my internet gets "stuck"(several times a day).

How you connected to the WAN ? PPPoE ? PPPoA ? Clean connection with dhcp ? Wireless ?

Yes, I'm connected to WAN. The Internet connection is just a plain ethernet connection with DHCP

IP address still exist on the WAN interface after "drop" ?

system log before and after may help...

Sorry for sounding naive, but by system log do you mean dmesg output?

@_DS_ Yeah, IP address still exists

dmesg, logread, both of them.
Also, are you tryed to ping internet hosts from router itself ? From "diagnostics" in luci, for example.

definitely unusual behavior. post some logs.

PS - that 30/30/30 reset stuff is some DD-WRT voodoo that is unnecessary here.

I have now reinstalled OpenWRT on the router without going through the Hard Reset procedure.

Dmesg didn't give any useful information but checking logread output indicated a problem with DNS. Pinging on the command-line confirmed this. I was able to ping IP addresses but not with hostnames. I suspect the previous problem of WAN unreachability was also due to DNS only.

Logread output contains the line `Fri Oct 10 06:24:46 2014 daemon.warn dnsmasq[1106]: possible DNS-rebind attack detected:`. And because of this, I guess DNS resolution is failing. I'm connecting my router to the Institute Academic network, so I don't think any DNS attack is going on. Also, I have never faced this problem when I directly connect my computer to the institute network.

Any suggestions on how to solve this now.

Dmesg output:
Logread output:

Is there any security implications for disabling rebinding protection.

This is weird. The WAN getting stuck problem has started again.

Pinging to even IP addresses is not working from the router. If I bring down the WAN link and bring it back up again using ifconfig, then ping works for a minute or so and after that again WAN becomes unresponsive. Checking dmesg and logread outputs revealed no new information.

Apart from all this, DNS is also not working.

Any help in this regard would be highly appreciated.

(Last edited by hashken on 10 Oct 2014, 21:39)

Install tcpdump on the router and check it on the packet level.

The discussion might have continued from here.