WRT54GL WAN DHCP lease time reaching 0

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kernel-panic69
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Joined: 08 May 2018
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PostPosted: Fri Jan 18, 2019 15:18    Post subject: Re: same problem with build 35531 on WRT54GL v1.1 Reply with quote
jwh7 wrote:
Bernie wrote:
But the problem disappeared when I turned off the "Shortcut Forwarding Engine".

DD-WRT v3.0-r35531 std (03/26/1Cool
ftp://ftp.dd-wrt.com/betas/2018/03-26-2018-r35531/broadcom/dd-wrt.v24_std_generic.bin


Interesting; I've always had it off on my k2.4 devices, as it should really default off anyway for pre-k3.10 builds, since SFE isn't supported on them. Sounds like the GUI is still doing something with it though...


The 2.4, 2.6, 3.2, and 3.5 kernel builds shouldn't even have that in the webUI page, whatsoever IMHO. It probably should be defaulted to 'off', or there should be a sticky note to turn it off.... Rolling Eyes
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jwh7
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PostPosted: Fri Jan 18, 2019 15:38    Post subject: Re: same problem with build 35531 on WRT54GL v1.1 Reply with quote
kernel-panic69 wrote:
The 2.4, 2.6, 3.2, and 3.5 kernel builds shouldn't even have that in the webUI page, whatsoever IMHO. It probably should be defaulted to 'off', or there should be a sticky note to turn it off.... Rolling Eyes
I told BS about it long ago, to remove or change the default on those targets. :-/
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# NAT/SFE/CTF: limited speed w/ DD # Repeater issues # DD-WRT info: FAQ, Builds, Types, Modes, Changes, Demo #
x64 OPNsense 19.7.7|FT2019.3: EA6900v1.1@1GHz, F7D8302|DD 41596: WNDR4500v2, WNDR4000@533, R6300v1,
E2500, E1500@353, WRT54*@250: GLv1.1 nsg, GSv6 µ, RT-N66U@663
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kernel-panic69
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Joined: 08 May 2018
Posts: 2691
Location: Texas, USA

PostPosted: Fri Jan 18, 2019 19:00    Post subject: Re: same problem with build 35531 on WRT54GL v1.1 Reply with quote
jwh7 wrote:
kernel-panic69 wrote:
The 2.4, 2.6, 3.2, and 3.5 kernel builds shouldn't even have that in the webUI page, whatsoever IMHO. It probably should be defaulted to 'off', or there should be a sticky note to turn it off.... Rolling Eyes
I told BS about it long ago, to remove or change the default on those targets. :-/


I think the problem is, there is no separate pages for non-SFE builds ... "one size fits all"... at least in the SVN tree, as best I can tell. I would have to dig to see if there is some kind of javascript or other function that is involved on what shows and what doesn't show or whatever. I guess to quote a movie... "at the whim of a madman..." Rolling Eyes
aehimself
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Joined: 19 Nov 2017
Posts: 22

PostPosted: Sat Jan 19, 2019 10:12    Post subject: Re: same problem with build 35531 on WRT54GL v1.1 Reply with quote
Bernie wrote:
But the problem disappeared when I turned off the "Shortcut Forwarding Engine".

DD-WRT v3.0-r35531 std (03/26/1Cool
ftp://ftp.dd-wrt.com/betas/2018/03-26-2018-r35531/broadcom/dd-wrt.v24_std_generic.bin


That's odd. I remember seeing this suggestion which I did try before experimenting with the external renew.
However, the earliest build I have in my config backups (I did one after each successful upgrade) was from 36330. Plus, I mostly used the mini builds. So it's possible that something happened between 35531 and 36330, or there is a difference between mini and std which breaks the SFE toggle.

Edit:
I went back to the beginning of this thread to get myself up-to-date with what exactly happened. And there's still an anomaly here:

aehimself wrote:
My ISP initially gives a 1 hour lease, after that a 24 hour one. I kept a close eye on the timer, as soon as it reached 30 minutes the lease time jumped up to 24 hours.


If it's the SFE, it works... once. Then it breaks.
I can not explain the first successful automatic renewal with anything else.
Bernie
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Joined: 18 Jan 2019
Posts: 2

PostPosted: Sun Apr 14, 2019 18:46    Post subject: WRT54GL WAN DHCP lease time reaching 0 Reply with quote
The problem of the lease timing-out after the first automatic renew (after a reboot) or after a manual renew (via the GUI) remains. The router temporarily stopped losing WAN access because it coincidently began receiving DHCP leases from my ISP that were longer than the time between weekly router reboots.

The DHCP leases have again become short (1 - 48 hours), thus allowing the "single automatic DHCP lease renewal" problem to again manifest.

My apology for confusion, fustration, or unnecessary diagnostic/analysis efforts resulting from my error.
aehimself
DD-WRT Novice


Joined: 19 Nov 2017
Posts: 22

PostPosted: Thu Apr 18, 2019 21:05    Post subject: Re: WRT54GL WAN DHCP lease time reaching 0 Reply with quote
Bernie wrote:
My apology for confusion, fustration, or unnecessary diagnostic/analysis efforts resulting from my error.


No need to apologize, no input is wrong (it works when..., it doesn't work when...) when it comes to development! Let's just hope that one day someone will get rid of this bug.
dTX
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Joined: 28 Dec 2018
Posts: 64

PostPosted: Fri Apr 19, 2019 23:52    Post subject: Reply with quote
Let me try to explain my findings(as i experienced the same stupid behavior in the past) and i hope it's not gonna get confusing.
So the culprit here is the udhcpc script as it is set by default(and never was corrected by the devs) to ask the ISP's DHCP for only one hour lease.And this is what most likely confusing the DHCP as it's usually is set to accept requests for something around 24 hours.So that's why every time one do release/renew the lease is weird(sometime is one hour only,sometime 15 hours and so on).I'm still testing this but if you run udhcpc with additional parameters to ask the DHCP for a normal lease time i think(in theory) this should fix that problem.I can say only one thing here,it's really depend on the ISP and how they set things on their end but that problem is very much present.
@kernel-panic69 i know you are on a newer build then me as i'm still waiting on <Kong> so let me ask you,is udhcpc still in play there when it comes to obtaining the IP,subnets,lease from the ISP or it's dnsmasq only(i'm kind of confused on how this should work)?
Give me so insights please so i can be prepare at least a little bit on what's coming.Thanks.

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kernel-panic69
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Joined: 08 May 2018
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Location: Texas, USA

PostPosted: Sat Apr 20, 2019 1:15    Post subject: Reply with quote
Yes, udhcpd has been removed. UdhcpC has not.
aehimself
DD-WRT Novice


Joined: 19 Nov 2017
Posts: 22

PostPosted: Tue Apr 30, 2019 16:28    Post subject: Reply with quote
dTX wrote:
the udhcpc script as it is set by default to ask the ISP's DHCP for only one hour lease.

dTX wrote:
but if you run udhcpc with additional parameters to ask the DHCP for a normal lease time i think(in theory) this should fix that problem.


I don't know too much about udhcpc, but this is not how a proper implementation of the DHCP protocol works. The lease is not defined by the Client (DD-WRT) at any time, it is always "offered" by the server (ISP) during the negotiation process. The Client has the authority to reject it, though. This is confirmed by the man page publishing no options to define this behaviour.

dTX wrote:
And this is what most likely confusing the DHCP as it's usually is set to accept requests for something around 24 hours.


Again, I have doubts here as the only automatic IP renewal happened after the initial 1-hour lease in my case. Like it's that's the only one which it could handle in my case.

dTX wrote:
I can say only one thing here,it's really depend on the ISP and how they set things on their end but that problem is very much present.


This is exactly what I was thinking back then. I know that there are a number of us who experienced this issue but it was not widespread enough for the devs to be forced to look into it. Also - unfortunately - I was unable to find a detailed thread with information I can compare (router model, ISP name, network captures, etc).

My guess is that the root cause will be some kind of compatibility issue (between chipset and udhcpc version for example) as:
1, it's present in a small number (special cases) only despite DD-WRT is used widely around the globe
2, using a different firmware solves the problem

Sorry about the first part of my comment, I don't mean to play the smart guy here I just don't think it's a path leading to a solution. As it is, we always can refer to Technet's whitesheet of DHCP:
https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-2000-server/cc958935(v=technet.10)
aehimself
DD-WRT Novice


Joined: 19 Nov 2017
Posts: 22

PostPosted: Thu May 02, 2019 17:58    Post subject: Reply with quote
dTX wrote:
So that's why every time one do release/renew the lease is weird(sometime is one hour only,sometime 15 hours and so on).


This actually got me thinking. I did a release-renew and the working firmware showed the same, initial, 1-hour long lease time from my ISP.
This way I can confirm that the weird lease times are indeed received and processed correctly by DD-WRT, it just fails to renew the second time / after longer lease times.
Could it be some kind of a memory shortage / buffer overflow on devices with low NVRAM? Confused
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