[Solved] Frequent Internet Disconnects

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renkforce
DD-WRT Novice


Joined: 18 Jan 2014
Posts: 15

PostPosted: Sat Jan 25, 2014 16:25    Post subject: [Solved] Frequent Internet Disconnects Reply with quote
Device information:
TP-Link WDR4900 V1
DD-WRT v24-sp2 (01/10/14) std - build 23320
Linux 3.10.26 #123 Fri Jan 10 07:45:59 CET 2014 ppc

My WAN link drops every 40-50 minutes for no reason. These reconnects cannot be traced back to my ISP.
I'm connecting via DHCP and not using any VPN at all.

Here is what happens in /var/log/messages:
Code:
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : vpn modules successfully unloaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_conntrack_proto_gre successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_nat_proto_gre successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_conntrack_pptp successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_nat_pptp successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: process_monitor : Process Monitor successfully stopped
Jan 23 21:44:13 ddwrt user.info syslog: process_monitor successfully started
Jan 23 21:44:13 ddwrt daemon.debug process_monitor[8403]: We need to re-update after 3600 seconds
Jan 23 21:44:13 ddwrt daemon.info process_monitor[8403]: set timer: 3600 seconds, callback: ntp_main()
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : vpn modules successfully unloaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_conntrack_proto_gre successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_nat_proto_gre successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_conntrack_pptp successfully loaded
Jan 23 21:44:13 ddwrt user.info syslog: vpn modules : nf_nat_pptp successfully loaded
Jan 23 21:44:14 ddwrt user.info syslog: wland : WLAN daemon successfully stopped
Jan 23 21:44:14 ddwrt user.info syslog: vpn modules : vpn modules successfully unloaded
Jan 23 21:44:14 ddwrt user.info syslog: vpn modules : nf_conntrack_proto_gre successfully loaded
Jan 23 21:44:14 ddwrt user.info syslog: vpn modules : nf_nat_proto_gre successfully loaded
Jan 23 21:44:14 ddwrt user.info syslog: vpn modules : nf_conntrack_pptp successfully loaded
Jan 23 21:44:14 ddwrt user.info syslog: vpn modules : nf_nat_pptp successfully loaded
Jan 23 21:44:14 ddwrt user.info syslog: wland : WLAN daemon successfully started
Jan 23 21:44:14 ddwrt user.info syslog: WAN is up. IP: 77.22.xxx.xxx


But why does it happen? There has to be a trigger.

What could be the reason for this?


Last edited by renkforce on Mon Jan 27, 2014 9:55; edited 1 time in total
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renkforce
DD-WRT Novice


Joined: 18 Jan 2014
Posts: 15

PostPosted: Sat Jan 25, 2014 18:23    Post subject: Reply with quote
Yes, I isolated the problem to the dd-wrt router.
Its verified by connecting the PC directly to the cable modem. Also there are no more interruptions if I use another router or the stock firmware from TP-Link instead of dd-wrt.
renkforce
DD-WRT Novice


Joined: 18 Jan 2014
Posts: 15

PostPosted: Sun Jan 26, 2014 0:49    Post subject: Reply with quote
Update: I noticed the reconnect occurs exactly once every 45 minutes.
renkforce
DD-WRT Novice


Joined: 18 Jan 2014
Posts: 15

PostPosted: Sun Jan 26, 2014 10:04    Post subject: Reply with quote
eibgrad wrote:
Is your router's clock keeping accurate time?

Yes, I am using NTP and the time is updated right after boot.

eibgrad wrote:
How long of a lease is the ISP providing for the WAN?

As far I can see the WAN lease time is 90 minutes.

eibgrad wrote:
When it fails, can you get reconnected by simply renewing the lease from Status->WAN?

I do not have to press or do anything. The router reconnects just within a second. (The log in the first post shows the whole reconnecting process.)

I did some research and read about some similar problems. One approach is to add a firewall exception which did not work for me:
http://svn.dd-wrt.com/ticket/973 (this might be the most detailed description so far, if that's my actual problem)
http://www.dd-wrt.com/phpBB2/viewtopic.php?p=785380
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=175072
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=28200
Source: https://encrypted.google.com/search?q=%22vpn+modules+successfully+unloaded%22+site:www.dd-wrt.com

It seems I just have to handle the strange DHCP behavior of my ISP.
Mile-Lile
DD-WRT Guru


Joined: 24 Feb 2013
Posts: 1628
Location: Belgrade

PostPosted: Mon Jan 27, 2014 8:13    Post subject: Reply with quote
See if this helps
http://svn.dd-wrt.com/ticket/3077
Mile-Lile
DD-WRT Guru


Joined: 24 Feb 2013
Posts: 1628
Location: Belgrade

PostPosted: Mon Jan 27, 2014 8:14    Post subject: Reply with quote
See if this helps
http://svn.dd-wrt.com/ticket/3077
renkforce
DD-WRT Novice


Joined: 18 Jan 2014
Posts: 15

PostPosted: Mon Jan 27, 2014 9:52    Post subject: Reply with quote
Finally I was able to determine and solve the problem.
After I added a firewall exception allowing inbound DHCP traffic, my connection still dropped after exactly 45 minutes.

Then I decided to handle the lease by myself and was able to renew the DHCP lease right before the drop would normally occur. This prevents the WAN disconnect/reconnect.
Code:
kill -USR1 `cat /var/run/udhcpc.pid` 2> /dev/null


To make this permanent, I created a crob job under Administration -> Management to renew the lease every 20 minutes. You should pick an interval less than half your lease time.
Code:
*/20 * * * * root /bin/kill -USR1 `/bin/cat /var/run/udhcpc.pid` 2> /dev/null


Thanks for your help on IRC and the forums.
rambotech
DD-WRT Novice


Joined: 27 Sep 2012
Posts: 4

PostPosted: Wed Sep 25, 2019 12:07    Post subject: Reply with quote
renkforce wrote:
Finally I was able to determine and solve the problem.
After I added a firewall exception allowing inbound DHCP traffic, my connection still dropped after exactly 45 minutes.

Then I decided to handle the lease by myself and was able to renew the DHCP lease right before the drop would normally occur. This prevents the WAN disconnect/reconnect.
Code:
kill -USR1 `cat /var/run/udhcpc.pid` 2> /dev/null


To make this permanent, I created a crob job under Administration -> Management to renew the lease every 20 minutes. You should pick an interval less than half your lease time.
Code:
*/20 * * * * root /bin/kill -USR1 `/bin/cat /var/run/udhcpc.pid` 2> /dev/null


Thanks for your help on IRC and the forums.


I have Spectrum in Florida (previously Bright House), and had the same issues. This solved the problem for me as well.
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