Yet another "Your ISP's DHCP does not function correctly" thread

[harrenkyym]

Hi, all.

I have an ASUS RT-AC68U in my beach house. I just came here and I noticed internet wasn't working. I've been out for three weeks and when I left everything was working. I had this problem once like a month and a half ago, but I could solve it by changing the mode to "normal mode" (I thought it was that). So when I came a few days ago I thought that it would be kind of easy to solve it again... but here I am, two days later at 5 am becoming crazy. I've tried EVERYTHING. I've switched back to my ISP router (and it works), I've introduced again the gpon password to my ONT because I noticed it was blinking and now it is solid green again, I've done a factory reset twice, I've restarted my router and my ONT like 324234 times, I've switched to "continuous mode", I've upgraded my fw (merlin's last one), I've tried the script thing to restart when DHCP is down, I've cloned my ISP's router MAC... I don't know what else to do. I've followed every method in this forum, I'm driving nuts. I'm starting to suspect that my ONT has been banned suddenly or something like that. It is a ZTE ZXA10 F601, it's been working for years but now... I don't know. I don't know what else to think, to try... Is that even possible that my ISP (a spanish one called Pepephone) can do something like that? If so... why did I have that same problem like six weeks ago and I could solve it "easily" after a few hours of troubleshooting and now it's like IMPOSSIBLE to fix it? I'm so hopeless right now after a few days of trying and trying and trying.

Thanks at least for reading. Have a good day.

 

[L&LD]

What firmware are you running?

Are you using a saved backup config file after doing a proper reset?

[Wireless] ASUS router Hard Factory Reset | Official Support | ASUS Global


What features, options, and scripts are you using, past defaults, if any?

 

[Jaime Alvarez]

I can think of two things:

• Just in case... check that you cloned the WAN MAC correctly. They usually have it printed out in the router's case.
• Ca you put the ONT in bridge mode? Then you could use the ASUS router for managing the connection directly.

 

[JR256]

If your modem has multiple rj45 ports, try a different one. This used to work for me on my old modem that had this issue sometimes.

 

[MamaLing]

I had the exact same problem, started last night. I did a lot of research, because after some tests, it turned out my Asus RT-AC68U router caused the problem. I've tried many, many things that some suggested on this forum, but eventually the script helped solve the problem. Read this I was shocked when I realized that developers know about this issue for so long and it hasn't been fixed in any firmware. That's disappointing. BTW I installed Merlin's 386.5_beta1 firmware. If you could fix your issue, I recommend making a backup file about the settings in the router, because there's a chance you need to do a factory reset...

 

[harrenkyym]

@L&LD

- As I said, I updated the fw so right now it is Merlin's 386.5. Before that I updated the firmware like a few months ago, so it hasn't been really outdated when the problems started.
- I'm not using any saved backup config after the factory reset (using WPS button, etc.)
- The script I was using (I installed it trying to repair this problem) is the one the @MamaLing is suggesting. Didn't work for me. Now I don't have because I did the factory reset. It's clean.

@Jaime Alvarez

- I cloned it correclty, I didn't even use the MAC on the sticker under my ISP's router, I checked it in the router's menu, that way I was 100% sure it was the correct MAC.
- I will try, but I think I haven't seen the option, it's a very basic ONT. And as far as I know... it could be working perfectly and the problem should be on the router (as many people have the same issue and it's not an ONT issue for none of them).

@JR256

I don't have a proper modem, I have the router+ONT. And it only has one port, from the ONT to the WAN port (I've also tried to make a Dual WAN net and switch ports between WAN port and LAN1, but as everything, it didn't work.

@MamaLing

I've already tried that script, that's the script I was talking about... Nothing. But truth be told, when I type "cru l" I don't see any job listed. Scripts are enabled, the files at jffs/scripts are ok, everything is good, the permissions are well set, I've restarted the router... I don't know what's going on, I don't know if the script is running or not and checking the logs... I don't see anything. :/
EDIT: I started it manually, because it's not starting when I reboot the router, I don't know why. So for the moment it is restarting again and again without any changes.

 

[Tech9]

I've switched back to my ISP router (and it works)

As a last resort, use the ISP provided router to establish the connection (with wireless disabled) and your Asus router in double NAT behind it. If the connection is still unstable, call your ISP to fix. It's their device now not working properly and can't blame your equipment behind it. You lose nothing (some extra power consumption) and may get extra security benefits (your devices behind two firewalls).

 

[harrenkyym]

As a last resort, use the ISP provided router to establish the connection (with wireless disabled) and your Asus router in double NAT behind it. If the connection is still unstable, call your ISP to fix. It's their device now not working properly and can't blame your equipment behind it. You lose nothing (some extra power consumption) and may get extra security benefits (your devices behind two firewalls).

I wouldn't like to do that. In my house and my beach house I've been using an asus router + basic ONT for ages without problems. Extra power consumption is important for me because it's getting more and more expensive every day. A few week ago the price for the MWh was 700€ in Spain. Now the cost is more than 200€, so... I don't really wanna pay more.

 

[Tech9]

I've never seen the issue personally, but there are multiple threads about it with no universal solution. The only guaranteed fix is using ISP equipment and whatever you want behind it. Otherwise you may have to replace your Asus router with something else and hope the issue never happens again.

 

[sfatula]

I used a script also to first reset network, then reboot ASUS, then if still not fixed cycle power on it. But I have equipment that allows me to do that. Since it's automated, it solves the problem quickly. But I also have had this problem for many years.

 

[drinkingbird]

Hi, all.

I have an ASUS RT-AC68U in my beach house. I just came here and I noticed internet wasn't working. I've been out for three weeks and when I left everything was working. I had this problem once like a month and a half ago, but I could solve it by changing the mode to "normal mode" (I thought it was that). So when I came a few days ago I thought that it would be kind of easy to solve it again... but here I am, two days later at 5 am becoming crazy. I've tried EVERYTHING. I've switched back to my ISP router (and it works), I've introduced again the gpon password to my ONT because I noticed it was blinking and now it is solid green again, I've done a factory reset twice, I've restarted my router and my ONT like 324234 times, I've switched to "continuous mode", I've upgraded my fw (merlin's last one), I've tried the script thing to restart when DHCP is down, I've cloned my ISP's router MAC... I don't know what else to do. I've followed every method in this forum, I'm driving nuts. I'm starting to suspect that my ONT has been banned suddenly or something like that. It is a ZTE ZXA10 F601, it's been working for years but now... I don't know. I don't know what else to think, to try... Is that even possible that my ISP (a spanish one called Pepephone) can do something like that? If so... why did I have that same problem like six weeks ago and I could solve it "easily" after a few hours of troubleshooting and now it's like IMPOSSIBLE to fix it? I'm so hopeless right now after a few days of trying and trying and trying.

Thanks at least for reading. Have a good day.

Do you have Guest Network 1 configured? If so, it is a bug. My guess is you are losing internet when a guest connects to the guest network, or something on the guest network renews its lease (which it will do every 24 hours or so)? GN1 is forwarding LAN DHCP queries to the WAN causing a conflict and blocking the router WAN IP from being able to reach the internet. This seems to only affect ONT customers as the ONTs apparently strip off the VLAN tag from the rogue DHCP packets (otherwise they would not get through and would not be a problem).

If not using guest, your router may simply have died. If your ISP router works, your ONT isn't banned or anything. However with all the troubleshooting you've done, you may just be running into the fact that they limit you to 1 IP lease and it isn't expiring with all the testing you're doing. If your ISP router is the last one that worked, plug that in, make sure it gets an IP, then find the place in their GUI where you can release the WAN lease. Do that, wait a couple seconds til it says it is gone, then unplug the power cord. You now have freed up your lease.

Then before plugging the WAN to the Asus, go into the GUI, do the factory reset with initialize settings checked off. Then put in just a basic config to get into the router, check off "format JFFS", hit apply, then reboot twice, waiting 5 minutes between reboot 1 and 2. You now have a clean factory fresh config.

If your ISP does not require you to use their MAC address, then you should be ok leaving that part off. But if they do, configure that before plugging in the WAN also, and make sure you're using the right format that the Asus wants. Plug in the WAN, and make sure you get a WAN IP now. If not, then there is definitely something wrong.

You mention something about a password, does your ISP use PPPoE? If so make sure that is configured on your Asus. It is possible they have it built into their router but you need to manually put it in yours. Maybe a new requirement? From what I recall, with PPPoE you need to have the settings right before you'll get a WAN IP.

Anyway, if you do get to the point where your Asus WAN gets an IP, you can now re-enter all your configs (manually, not from backup) but use Guest Network 2 or 3, NOT 1. The problem should be resolved for good.

There is always the possibility that your ISP has implemented some new thing to only allow their own hardware to connect (using authentication etc). If none of the above works, you may need to do some research and see if that ISP has instituted any new measures. Unfortunately if nothing here works, I'd say your Asus may be hosed. But you can test by plugging it into the ISP's router (ASUS WAN to ISP LAN) and see if you get a WAN IP (it will be private one like 192.168.x.x). If you do and none of the stuff above works, then well I'm at a loss as to what it is.

 

[drinkingbird]

I've never seen the issue personally, but there are multiple threads about it with no universal solution. The only guaranteed fix is using ISP equipment and whatever you want behind it. Otherwise you may have to replace your Asus router with something else and hope the issue never happens again.

There does seem to be a universal fix now, at least for people behind a fiber ONT who are using a Guest Network, see my post above. The problem was discovered by @CoyoteDen quite a while ago but as of yet Asus has not done anything to fix it. The issue has existed in all the 386 builds.

However the "Your ISP's DHCP does not function properly" is a generic error and can point to other things as well, but most of the people I've seen with this issue are on FIOS and I suspect are using Guest Network 1.

 

[drinkingbird]

I can think of two things:

• Just in case... check that you cloned the WAN MAC correctly. They usually have it printed out in the router's case.
• Ca you put the ONT in bridge mode? Then you could use the ASUS router for managing the connection directly.

The ONT is a bridge, it has no other modes. You're thinking of the FIOS router but sounds like OP isn't using that (except for testing).

As long as you release your DHCP IP from the ISP router (or wait a couple hours), there is no need to clone the MAC to your own router on FIOS (unless your particular ISP has some special requirement, Verizon doesn't, not sure about Frontier or others). But it won't hurt anything either. If you're getting an IP and have internet, then lose it, it isn't to do with MAC cloning. If they are filtering on MAC, it won't work at all.

 

[drinkingbird]

I had the exact same problem, started last night. I did a lot of research, because after some tests, it turned out my Asus RT-AC68U router caused the problem. I've tried many, many things that some suggested on this forum, but eventually the script helped solve the problem. Read this I was shocked when I realized that developers know about this issue for so long and it hasn't been fixed in any firmware. That's disappointing. BTW I installed Merlin's 386.5_beta1 firmware. If you could fix your issue, I recommend making a backup file about the settings in the router, because there's a chance you need to do a factory reset...

You don't need that script, cycling the WAN is just a temporary fix and you'll still have brief outages. If you're using Guest Network 1, see my other post, move to GN2 and your problems should go away.

 

[sfatula]

No GW1, no fiber here. Plenty of threads with a lot of theories, seems to be many different cases perhaps. My script works perfectly and problem goes away. Rebooting router always fixes the issue for me.

 

[drinkingbird]

No GW1, no fiber here. Plenty of threads with a lot of theories, seems to be many different cases perhaps. My script works perfectly and problem goes away. Rebooting router always fixes the issue for me.

Yeah where you said many years I assumed yours was a different issue. This bug started with the 386 code base. Perhaps your router is having heat issues? Has it happened with different routers or just one for years? If just one, I'd say you have an issue with the router itself. DHCP seems to be one of the first things that starts acting up when things are too hot or when a router is dying.

 

[sfatula]

I replaced an Asus router with another brand new one, same issue.

 

[drinkingbird]

I replaced an Asus router with another brand new one, same issue.

What sits off the WAN port, a cable modem? Modem could be bad or the coax to it could be dropping some packets (DHCP is very sensitive). Could even be the ethernet cable between your router and modem.

Or your ISP could just have flaky DHCP. You could try the various DHCP settings (aggressive, continuous, normal) to see if that makes any difference. Continuous or aggressive isn't necessarily better, your ISP could be limiting the number of DHCP requests you can send in which case Normal might be better.

Even though rebooting the router or cycling the WAN fixes it that doesn't necessarily mean it is the router, that just causes it to renew its lease again.

Just some thoughts, if what you have is working for you then no big deal. But if your signal to the modem isn't good or it is dropping packets, I suspect your internet experience isn't what it could be.

 

[sfatula]

I've done all those checks and many many more. It's the software on Asus. Many many folks here with same issue. Many threads.

 

[drinkingbird]

I've done all those checks and many many more. It's the software on Asus. Many many folks here with same issue. Many threads.

If you're referring to the "ISP's DHCP" error that is because it is a generic error that applies to many different issues. Obviously it isn't strictly the Asus software, it is something to do with a certain combination, as the majority don't have any issues. If only ASUS routers do it in your case then perhaps there is something strange to do with your ISP's DHCP or next hop router that isn't interacting correctly. Similar to what I experienced where only FIOS users seem to be affected by the "rogue DHCP" bug because of the way the ONT works. If no other brand of router has the issue in your case, then there may be some similar unexpected behavior in your case.