Your ISP's DHCP does not function correctly

[johndoe0511]

I have an Asus RT-AC66u that shows this message any time my ISP (Charter in Georgia) drops the connection, which has now become every few days. My only recourse is to power cycle the cable modem. I've had Charter out to check the line and modem and they say everything checks out.

In researching this, I've come to find out this seems to be an Asus thing. I use the Merlin firmware, and this has happened with multiple versions. It also happens with the Asus firmware. I've seen some suggest that changing the DHCP query frequency from aggressive to normal fixed the issue for them, but mine was already set on normal. My parents have an RT-AC68u, also on Charter (but in a different state) and they have no issues whatsoever. For that matter, mine used to work. But then this started happening suddenly and it's never worked normally again.

Is there anything else I can check or do? I hate to buy another router, but having my Internet routinely go out on my security cameras isn't an option. Regarding new routers, are there ones I should look into? Is this really mostly just an Asus issue? I don't want to spend $200+ only to have the same thing occur.

Thanks

 

[outlaw78]

I have had the same thing happen to me on charter. Mine happens when I use "Mac Clone" under WAN. Are you using Mac clone?

 

[MFM000]

Happens to me with Cox.
Most of the time going to WAN->Internet Connection and invoking the "Quick Internet Setup" button in the upper LH corner
and allowing it to time out works (will hang for a while then reset).

Unplugging cable modem for 10 min usually solves the remaining ones.
(Somehow you need to get the cable co to "forget and start over".

 

[Joboo7777]

Happened to me when I moved from 380 to 382. Not sure the resolution as I did a few things during the issue. I think it most likely was resolved by waiting a while to re-connect to the network. Interested to see if this will happen again when I upgrade to 384 as I plan to reset back to factory when upgrading.

 

[tck81]

I had this problem when upgrading from 380.68_4 to 380.69 on 2 different 68u's. I did a factory reset and set both of them up from scratch and they connect pretty much instantly and I've yet to get this message.

 

[Stephen Becker]

I have seen the same thing. My modem takes a very long time to boot, so I assume the problem is that the router starts up before the modem is ready. It appears like uhdcpc does not retry getting an IP address if it fails the first time (not sure why, I verified the -n flag is not set, which would explain that functionality). Most DHCP clients will send a broadcast looking for an IP address every 5 minutes if it doesn't have a lease. I have left mine running all night and it does not fix itself. Opening the WAN page and pressing Apply seems to fix the problem, which proves it is just a DHCP client problem on the router.

I wrote this script today (so haven't fully tested it), but it pings Google's DNS every 5 minutes, if any fail, it will ping 10 times (2 seconds between each) and if all fail will release/renew your WAN interface, if any of the pings reply, it goes to sleep for 5 more minutes and loops. You could make this your wan-start script...I am not sure if it is safe to have that be a never ending script. What I did was name this script net-test and then put the follwing in my wan-start script nohup /jffs/scripts/net-test >/dev/null &

#!/bin/sh

intadr="8.8.4.4"
pausetime=300
retest=10

while true;
do
sleep $pausetime

i=$retest
while ! ping -c1 $intadr
do
i=$(($i-1))
if [ $i -lt 1 ]
then
logger "Failed test to $intadr, Renewing DHCP..."
killall -SIGUSR2 udhcpc
sleep 2
killall -SIGUSR1 udhcpc
break 1
fi
sleep 2
done
done

 

[Joboo7777]

This just happened to me again last night after resetting router to default settings. I tried everything, Reset the modem, reset the router(3100). When the modem is reset and also used as a router it seems to work. But when I put into bridge mode I get the same message from the router. I finally just gave up and set up my asus as an AP and connected to the Cablem Mode(now acting as router). Need to try again today.

 

[Joboo7777]

I was able to solve my issue(for now). I ended up replacing the cable modem(TC8715D) with a Netgear CM600.

FYI.. Another step I tried before replacing the modem was connecting a laptop directly to the TC8715D modem. initially this did not work. Opened a command prompt and had to perform an ipconfig /release, then /Renew and all worked. I tried the equivalent on the router but did not get same results.

 

[Joboo7777]

I was able to solve my issue(for now). I ended up replacing the cable modem(TC8715D) with a Netgear CM600.

FYI.. Another step I tried before replacing the modem was connecting a laptop directly to the TC8715D modem. initially this did not work. Opened a command prompt and had to perform an ipconfig /release, then /Renew and all worked. I tried the equivalent on the router but did not get same results.

Ok. last post on this. I ended up taking back the CM600 because a technician from spectrum(My ISP) stated 1GB service was coming in the next month and they would be providing a modem at no cost. In the interim, I figured I try and get the TC8715D working. Even if I had to use it as a router, knowing 1GB service with modem was coming was worth it. I did some additional research and found a thread on a forum that stated although bridge mode was enabled, DHCP on the TC8715D still remained active. So before I put the device in bridge mode I disabled DHCP, then activated bridge mode and all worked!

Wanted to post this just in case someone else has the same issue.

 

[follower]

You guys use 2 routers at the same time. Those cable modems have a router function. That makes a lot of problem just like you guys have.
Do not use 2 router as a router mode. One of them should be disabled.

If you really want to use a router from a market there are various way to fix or use it properly .

1. Use a 'bridge mode': I recommend this.
2. Use a switch to get a second physical IP Address if your ISP allows or provides you to use an extra IP Address: If you use IPTV you must buy a switch which supports IGMP.
3. Disable some functions such as DHCP, WAN, NAT etc from your router which is not from ISP: This router works as a switch. The purpose of this is a port extension.
4. Use a pure cable modem: This one is the best.

Before you do this search and learn how to do it first ok?

 

[Joboo7777]

You guys use 2 routers at the same time. Those cable modems have a router function. That makes a lot of problem just like you guys have.
Do not use 2 router as a router mode. One of them should be disabled.

If you really want to use a router from a market there are various way to fix or use it properly .

1. Use a 'bridge mode': I recommend this.
2. Use a switch to get a second physical IP Address if your ISP allows or provides you to use an extra IP Address: If you use IPTV you must buy a switch which supports IGMP.
3. Disable some functions such as DHCP, WAN, NAT etc from your router which is not from ISP: This router works as a switch. The purpose of this is a port extension.
4. Use a pure cable modem: This one is the best.

Before you do this search and learn how to do it first ok?

Absolutely agree. The morale of the story is, even if you enable bridge mode, you should disable DHCP and other services.

 

[el pescador]

I get this when i set the 2 in 1 to bridge mode.
When it does connect i still cant access the net.

Funny thing is i tried it a few merlin versions ago and it worked.
But decided to upgrade to a newer beta and it stopped working.

Tried twice since with newer firmware , factory resets etc still no luck.

Cant remember the firmware it worked on.

Had to set vlans in the iptv section.....ive tried both vlan codes orange and jazztell.

I dont want the tin can isp router to manage a thing.
I dont mind losing the phone.

I just want the asus to manage everything.

Orange espana...with the livebox fibra piece of junk.

Any with a similar issue?

 

[Joboo7777]

Before putting into bridge mode did you try turning off DHCP on the modem?

 

[el pescador]

no....will try that though
It worked once so not sure why it wouldnt work after?

Anyone with orange espana?

 

[el pescador]

Doesnt work.

I seem to have a static wan ip address.
I know they wont give me the gateway or subnet mask....any ideas?

 

[Joboo7777]

Doesnt work.

I seem to have a static wan ip address.
I know they wont give me the gateway or subnet mask....any ideas?

I wish I did. Now I’m wondering if I really solved my issue by turning DHCP off or if I just got lucky.

 

[el pescador]

Wish i wasnt on static then it would connect so ive been reading.

Been told to try hooking it up but keeping the asus on the same dhcp subnet ie....192.168.1.2 and pinging the ONT (192.168.1.1) from a device through the asus .....something to do with dhcp being a mess historicaly...wont bore you.

Also told to leave it for an hour and it might connect...lol

 

[johndoe0511]

Hey folks, just wanted to follow up. I had given up on my Asus RT-AC66u (original version) and was researching routers the past few days. In the course of that I ran across someone talking about Rogers in Canada, and he casually mentioned making sure IPv6 was disabled. So I checked mine, and it was enabled. I disabled it, and so far I've booted about 10 times & reconnected seamlessly every time. I also checked my parents' RT-AC68u, also with Charter, but in a different state (which I know can be handled differently), and they have IPv6 disabled. They've never had issues. I set up both theirs and mine, but I did do a factory reset on mine probably a year ago, and that's where it got enabled.

I'm not prepared to say that's the ultimate fix until I've had Charter change my IP multiple times and I've done another couple dozen reboots. But so far it's looking good. I'm curious as to the IPv6 status of some of you who replied, and if it makes a difference for you.

 

[Brady Holt]

I fixed this by using these WAN settings:

"DHCP query frequency" -> "Normal"
"Extend the TTL value" -> "Yes"
"Spoof LAN TTL value" -> "Yes"

 

[Jack24000]

I fixed this issue with my Asus RT-AC3200 simply by doing a firmware update. I tried almost everything else in this thread to no avail.