ASUS firmware DHCP "Continuous Mode" potential fix for "ISP's DHCP did not function properly"

[Mattias]

Agree. In the past the method of turning off and on wan has worked rarely. Rebooting router is usually needed.
Hopefully 386 firmware line will be better.

Well bad news... I use 386 official now, so can't say much yet(installed it today), but in beta 386 I had those issues also.

 

[spyderryan]

How did I not see this thread before!! This makes total sense for my situation. My ISP is continuously changing my WAN IP Address. Consequently the router (Asus RT-AX86U running Merlin FW 386.1_beta5) goes unresponsive. Only a reboot helping in this case.
Just changed to Normal mode (potentially to Continuous mode if this fails). I'll monitor and feedback my results.
386.1 is also on deck, but only changing 1 thing at a time.

 

[spyderryan]

Not a huge change. Currently running Continuous mode. Getting a reset (or a few) every other day.

 

[Zonkd]

Not a huge change. Currently running Continuous mode. Getting a reset (or a few) every other day.

I was finally able to fix the problem by getting a static IP from my ISP. Continuous mode, factory resets and firmware upgrades never solved it. If you can’t get a static IP then this script might be helpful:

Restart WAN interface when internet is down

Third party firmware for Asus routers (newer codebase) - RMerl/asuswrt-merlin.ng

github.com

 

[Vidgamer]

It was starting to drive me batty, getting kicked offline every couple of days. "Normal" mode didn't seem to fix it, although I'd have to test it more to be sure. "Continuous" seems to have fixed it. It's been more than a couple of days being up.

I'm using an RT-AC86U connected to Spectrum's cable modem.

 

[Krackerjack]

I have the same issue with my Asus AC88U indicating "ISP DHCP does not work". I have Spectrum for my ISP. I have recently swapped out my modem and currently have a ES2251 modem. For the life of me I could not get the router to obtain an IP address from the new modem, unless I did a factory reset on the router. When I would load my original settings back into the router, it would refuse to obtain an IP address. I have never had issues before with getting a new modem and getting this router to work with it. No settings have changed between the many other modems I have had and this one.

Nothing worked with changing the WAN DHCP frequency. I tried all settings.
The only "Fix" I found was to either temporary change the SSID for my guest network (2.4G slot 1) to knock all guest devices offline, or enable "Access Intranet". Within 3-5 min the router was able to obtain an IP address from the modem. I know my modem has the admin panel disabled, but I can ping it successfully (192.168.100.1). I wonder if the guest network subnet is interfering with obtaining IP for some reason? The guest network subnet is 192.168.101.x when "Access Intranet" is disabled and it is 192.168.1.x when "Access Intranet" is enabled.

I upgraded my firmware to Merlin and the exact same issue happens, and I can work around it by temporarily changing guest network SSID or enabling access intranet.

Once I have a IP assigned on the WAN port, I can change my guest network SSID back/disable access intranet and things are fine.... until a power outage, reboot or DHCP lease expires... then I have to go through the process again.

Wondering if you guys are having the same issue?

 

[kennymc.c]

The error has occurred more frequently in the last few months with an AC86U. At the beginning, when it did not occur very often, I just re-plugged the LAN cable of the WAN port. This worked fine, because it occurred maybe 1 maxmimal 2 times a month. Interestingly MS Teams meetings were not interrupted during this time. I can then only no longer open or reload websites. I first thought of a DNS problem but I was also not able to open a website by its IP. The WAN port is connected to an ISP cable router (Arris TG3442DE), which still has internet access and DNS resolution also works.
However, on one day the error suddenly occurred several times a day, ending up almost every 5 minutes. I then reset the ISP router to factory settings, as I suspected that it might be due to its DHCP server. Unfortunately, it cannot be set to bridge mode due to ISP restrictions. But even after that I still had no internet. Only a reboot of the Asus router helped. In the days after that it was better again.
The DHCP query frequency was set to Agressive in the beginning, in between I set it to Normal, but that doesn't help much.
I then installed the script linked here on Github for an automated restart of the WAN interface and also monitoring reasons. I noticed that the error occurs about every 2-3 days 1-3 times per day. The WAN restart helped every time. As a test, I then also set the frequency to Continious. The error did not occur for several days, but then came back. However, not quite as often.

What I now notice is that after a WAN reset via the script, my VPN server no longer runs properly. In the GUI next to "Export OpenVPN configuration file" it says "Initialinzing the settings of OpenVPN server now, please wait a few minutes to let the server to setup completed before VPN clients establish the connection". The message doesn't disappear on its own and I can't connect to the server externally.
I then click Apply at the bottom everything works again. What could be the reason for this?

 

[vrapp]

I just had this inevitable round of troubleshooting of this error. It does occur whenever there's some change of the cable modem. It had been going on for years, and it's a shame that it still has no solution. I connect the laptop to the cable modem, and it immediately acquires DHCP and works. Then I connect the router and I already know how I will spend the next hour. This is how it was several years ago, this is how it is today. Today it's even worse because it appears that whenever the router can't connect DHCP, it seems to restart at least something - wireless connection gets dropped for some time, then restores. Plus everything is painfully slow, every page takes up to 30 seconds to refresh.

All the proposed "solutions" in this thread are practically useless. The issue always eventually repairs itself, even when you don't do any changes at all. So it most likely coincides in time with yet another effort and another change, and then the lucky owner posts "this worked". No, it did not, it's simply was the time for it to start working anyway. As I understand, nobody was ever able to consistently reproduce the problem and a solution.

Maybe Merlin could tell us what we need to do to have this DHCP problem finally resolved. Collective petition to Asus, perhaps?

 

[Ronald Schwerer]

I think you're right about the "fixes". I run into this problem only after making major changes on my router. I quit trying to fix it, just get a beer and wait. My ISP has a 30 minute lease, so average wait time for me is 15 minutes. Not worth going into Kabuli dance mode.

 

[sidlauskas]

Is there any other thoughts how this could be fixed? I'm using the latest official firmware in my AC66U, tried to reset it and use different DHCP modes (including the Continuous mode), but the internet still goes down every 24 hours (when the DHCP lease time expires)

 

[slvrscoobie]

Is there any other thoughts how this could be fixed? I'm using the latest official firmware in my AC66U, tried to reset it and use different DHCP modes (including the Continuous mode), but the internet still goes down every 24 hours (when the DHCP lease time expires)

Im getting this recently too. I switched from an AC3100 to an AX86U and found the performance wasnt worth it, so I went back to the AC3100. Now every day at 10am I lose WAN DHCP. just clicking 'apply' in the WAN config is enough to fix it, but it was literally rock solid for the last 4 years...

 

[Bmk]

I had the same problem,i was playing with my router rounds and rounds (discovering my ASUS GT-ax11000 and the its full potential‘s) i faced this issue disconnecting / IP conflict / ISP’s DHCP did not function properly ... and even tried more changing the source 5G router (‏ Huawei CPE pro 2 / Netgear Orbi) nothing worked

I tried all googled advices i could found nothing worked, then i remembered a silly mistake any beginner can do it

Before looking for sulotions please try this, maybe its cables issue

—————— The problem & The Solution———-
My mistake was I connected my asus router to the WAN/LAN ethernet

After changing the source port it worked, 100% back to life

it maybe not the same reason for all the cases, but this silly small mistake could happen to alot of users, hope this reply could help