Solved WAN DHCP renewal + VPN drops connection

raritywrt

Occasional Visitor
I am using an AC86U/AC2900 with the latest version (386.7_2). I reflashed the firmware, reset the router to factory defaults and then did a reboot with formatting of the JFFS2 partition. After that I only set up an OpenVPN connection to a NordVPN server (and touched no other settings).

My ISP has set the DHCP renewal time to just one hour:

1668438933677.png


It then seems to me like the current firmware waits until the lease expires (I saw it say Expired in the screenshot above), the connection goes down, then it renews it and the connection is restored. The result is that my connection is dropped 24 times every day.

This is the only thing I see happening in the system log:

Nov 14 14:16:57 rc_service: udhcpc_wan 8988:notify_rc start_dnsmasq
Nov 14 15:16:57 dnsmasq[2823]: exiting on receipt of SIGTERM

I tried reflashing to the original firmware and then the connection did not drop during DHCP renewal. I don't think I want to use the original firmware though since it doesn't seem to have a VPN killswitch.

Side question: Since my router won't receive as many frequent updates anymore, what is the most sensible/best upgrade when you don't need WiFi 6?
 

ColinTaylor

Part of the Furniture
If you think this is a bug in the 386.7_2 firmware I suggest you try 386.5_2 instead and seeing if that has the same problem.
 
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raritywrt

Occasional Visitor
Okay, I'm testing 386.5_2 now. I will know more in about 50ish minutes. Not sure I want to stay on that version considering both OpenSSL and OpenVPN is updated in newer releases though.

I got this screenshot right before the last DHCP renewal by the way:

1668445769636.png


Shouldn't the DHCP client ideally renew before the lease expires?

I also guess the AX86U is the natural upgrade from what I have. Other than WiFI 6 it doesn't seem to offer much, except being newer. Not really too keen on upgrading. The speeds of NordVPN is the limiting factor anyways (and not my hardware/router nor Internet connection).
 

ColinTaylor

Part of the Furniture
Shouldn't the DHCP client ideally renew before the lease expires?
The router should theoretically start attempting to renew the lease at the half way point. However, a 1 hour lease is rather short and may be confusing it (i.e. a bug). Even if the lease does expire the internet connection might not necessarily go down.
 
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raritywrt

Occasional Visitor
Unfortunately the same thing happens with 386.5_2. You can clearly see the DHCP renewal/connection reset within Traffic Analyzer on the router:

1668448963191.png


I could possibly get my ISP to increase the lease time by calling them, but I assume it would be nice to get this issue fixed as well. The latest release of the original Asus firmware did not have this issue as I mentioned.
 

ColinTaylor

Part of the Furniture
Can you post the complete router syslog for us to look at. It might help to diagnose where the problem lies.
 

raritywrt

Occasional Visitor
Will do. Give me about 50ish minutes. I just reverted back to the latest release again and set the log level to this:

1668451285913.png
 

ColinTaylor

Part of the Furniture
Setting it to this would be better:

Untitled.png

There's no real need to change the default message log level.

If you do the following you should see the renew message in the syslog:
Code:
touch /jffs/scripts/dhcpc-event
chmod 755 /jffs/scripts/dhcpc-event
But you also need to have enabled custom scripts in the GUI.

You can manually test the renewal by issuing this command:
Code:
killall -s USR1 udhcpc
Code:
Nov 14 19:02:22 custom_script: Running /jffs/scripts/dhcpc-event (args: renew)
 
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raritywrt

Occasional Visitor
Thank you. Attached is the system log.

Lease expired time:

Nov 14 20:29:23 custom_script: Running /jffs/scripts/dhcpc-event (args: deconfig 4)

Connection restored time:

Nov 14 20:29:28 WAN_Connection: WAN was restored.

Renewed time:

Nov 14 20:29:31 dhcp_client: bound XXX.XXX.XXX.XXX/255.255.248.0 via XXX.XXX.XXX.XXX for 3600 seconds.
 
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ColinTaylor

Part of the Furniture
Strange! I'm attaching the file fine, but when I save/post the reply it's gone.
It might contain keywords that are blocked by the forum's filter. Try uploading it to somewhere like pastebin.com and provide a link to it.
 

ColinTaylor

Part of the Furniture
That's very strange. I can't see any attempt by the router to renew the lease.

If you issue the following command do you see a renew message in the syslog and see the "Lease time" change in the GUI?

Code:
killall -s USR1 udhcpc
 

raritywrt

Occasional Visitor
Just tried it. The lease time did change:

1668461799755.png


But it's not reflected in the log:

syslog.txt

Maybe that's the issue. It isn't renewed before after the lease is expired and the WAN connection goes down.
 

dave14305

Part of the Furniture
Stop using Guest Network #1 and see if it stabilizes. There were reports of odd WAN DHCP behavior when GN #1 was in use.

I can’t find the thread at the moment, but it came down to a Guest Network #1 client would “steal” the WAN lease. If I find the thread later, I’ll edit this post.

EDIT: maybe not the case, since its not clear you use GN1, even though dnsmasq reserves the dhcp range.

EDIT2: found the post:

 
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raritywrt

Occasional Visitor
That was right after I ran your killall command.

dave15305: I stopped using the guest networks a while back for what you're mentioning.
 
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