Losing Internet (WAN) connection: ASUS RT-AC88U

Mike-48

Occasional Visitor
I'm having a problem that eludes my troubleshooting abilities. The setup is
  • Comcast/Xfinity
  • Netgear CM1150V cable modem
  • ASUS wireless router RT-AC88U (5.5 yr old)
  • Latest Merlin firmware (386.3_2)
Everything runs fine for days or weeks, then the router loses its Internet (WAN) connection. Symptoms:
  • Cable modem indicates all is OK. (All lights as they should be.)
  • Router Web interface indicates "Disconnected" from WAN.
  • WAN cannot be connected by rebooting the router via Web interface. (When it reboots, it has the same problem.)
  • WAN can be connected by power-cycling the router. (When it reboots, all's OK.)
Any ideas? I am thinking of either reinstalling the ASUS firmware (which is a pain, and I rather doubt will fix this) or replacing the router, under the hypothesis of some intermittent hardware failure. But I'd like to hear better ideas!

P.S. Does anyone know whether the RT-AC88U has gone through much revision in its relatively long life in the ASUS lineup?
 

L&LD

Part of the Furniture
Welcome to the forums @Mike-48.

Are you using all the ports on the RT-AC88U? They're known to be problematic (particularly Ports 5-8).

You may want to buy a cheap switch and use a LAN port as the WAN port instead. This may be all that is required to 'solve' this issue for you today.
 

Mike-48

Occasional Visitor
Welcome to the forums @Mike-48.

Are you using all the ports on the RT-AC88U? They're known to be problematic (particularly Ports 5-8).

You may want to buy a cheap switch and use a LAN port as the WAN port instead. This may be all that is required to 'solve' this issue for you today.
Thanks for the reply! I thought I answered your post but don't see my reply here.

Besides the WAN port, I'm using only ports 1-2 of the RT-AC88U, which form a bonded connection to a TP-Link T1600G-28TS smart switch. Everything else on Ethernet is hooked up to that switch. (I added the switch to prioritize my audio system on our network.)

Based on posts describing similar problems, I went into the RT-AC88U Web Interface and changed Advanced Settings > WAN > DHCP Query Frequency from "Normal Mode" to ""Aggressive Mode." I don't know if that will help, but it's cheaper than replacing the router.
 

Tech9

Part of the Furniture
Known issue with mixed results solutions:


Many more threads on the same subject.
 

Mike-48

Occasional Visitor
Known issue with mixed results solutions:

Hmmm.... Looks like I should consider swapping out the router. With what? becomes the question then.

@L&LD - You've advocated the ASUS RT-AX88U. Do you think switching to it would resolve this issue? The RT-AC88U meets my needs otherwise. But for various reasons, losing the WAN connection, even if every few days, is becoming intolerable.
 
Last edited:

L&LD

Part of the Furniture
I have, but the RT-AX86U surpassed it now. Actually, for almost a whole year today.
 

Tech9

Part of the Furniture
Hmmm.... Looks like I should consider swapping out the router.

Not a guaranteed solution. Read the related threads - many different Asus models with the same issue.
 

Mike-48

Occasional Visitor
Not a guaranteed solution. Read the related threads - many different Asus models with the same issue.
For that reason, I'll probably switch vendors. Maybe get a TP-Link AX11000. Or maybe it's time to go to a commercial-grade router.
 

Tech9

Part of the Furniture
It's up to you. Folks with ISP provided modem/router have one guaranteed solution - ISP equipment in router mode makes the connection and Asus in double NAT behind it. The issue is somewhere in Asuswrt code, in my opinion. Some incompatibility with specific modems.
 

Morris

Very Senior Member
I'm not convinced this is your router. Try disconnecting the jumper cable and then reconnect. If the link dose not come up, try connecting a PC to the modem. If the PC dose not get an IP and work on the internet, then the modem is at fault.

Good luck,

Morris
 

Morris

Very Senior Member
Even though power-cycling the router fixes it?

Next time it happens, I'll connect a laptop directly to the modem and see what happens.
I'm sorry, I did not notice that. Have you tried setting "DHCP query frequency" to "continuous"?
 

Mike-48

Occasional Visitor
Have you tried setting "DHCP query frequency" to "continuous"?
I just changed it from the default to "aggressive" and haven't had an issue since. However, it's only been a few days, and the issue occurs only once every few weeks. We'll see....

P.S. I enjoyed looking at your beautiful photos. Sorry that my walls already are full. If I ever get an (acoustic) art panel made for my audio room, I'll ask you to quote use of one of your images.
 

Morris

Very Senior Member
I just changed it from the default to "aggressive" and haven't had an issue since. However, it's only been a few days, and the issue occurs only once every few weeks. We'll see....

P.S. I enjoyed looking at your beautiful photos. Sorry that my walls already are full. If I ever get an (acoustic) art panel made for my audio room, I'll ask you to quote use of one of your images.
Thank you Mike, I've won many awards for my photography.

To me it seems there is a handshake issue between the modem and the router. The modem is not dropping the ethernet link when the coax side goes down. You are hardly alone having issues. I did a search and this was the first one I found:

It appears that the modem is also a router and thus it dose not make sense to drop a LAN side connection. Bad design. If you wan leas expires, I bet the router would have a successful DHCP renewal. I looked at the modem manual and they don't talk about how to configure it. I'm thinking a one minute to 5 minute DHCP lease from the modem would get you back up quickly. That's actually very little overhead. I did note that people with other brand routers have similar issues. At least your drops are not as frequent as some. If you have smart IOT, you could use a smart plug for your network gear and toggle it when internet goes down.
 

Mike-48

Occasional Visitor
To me it seems there is a handshake issue between the modem and the router. The modem is not dropping the ethernet link when the coax side goes down. You are hardly alone having issues. I did a search and this was the first one I found:
Morris, I appreciate your efforts. The user in the linked post has a different problem from mine, in that he has to reboot his cable modem when things go south, but I have to reboot my router. When he has trouble, the cable modem indicates no WAN connection, but when I'm having trouble, all the lights on the modem indicate normal operation.

Still, I don't rule out that rebooting either device could fix a handshake issue.

While I'm glad the issue occurs only once every several weeks or so, that makes it difficult to diagnose.
 

Morris

Very Senior Member
Morris, I appreciate your efforts. The user in the linked post has a different problem from mine, in that he has to reboot his cable modem when things go south, but I have to reboot my router. When he has trouble, the cable modem indicates no WAN connection, but when I'm having trouble, all the lights on the modem indicate normal operation.

Still, I don't rule out that rebooting either device could fix a handshake issue.

While I'm glad the issue occurs only once every several weeks or so, that makes it difficult to diagnose.
Yes, intermittent is difficult. I think I've seen someone post that they have a script that tests if the Internet is up and when it goes down they reset the interface. That would get you back quickly. I suspect you have the same issue as the person in the post I pointed to in that the LAN port on the modem dose not go down.

Dose your modem always give you the same IP? If it dose, set up a static IP on your router and your problems will be hoiden as traffic will flow as soon as the cable link comes back up. You will need to assign DNS in the wan interface.

Morris
 

Mike-48

Occasional Visitor
Does your modem always give you the same IP?
It is not guaranteed by Comcast, so I would not like to rely on it. A guaranteed static IP address is an additional monthly charge, I think a substantial one.

--- rant on ---
If this issue is caused by the failure of the modem to reset the LAN link after recovering from a failure (which seems plausible), it's hard to know what to call it. Is it a flaw in the modem (for not resetting) or in the router (for not adapting somehow). Which manufacturer to hammer on, trying to get a solution?

And if the only solution is to throw money at the problem? Replace the modem? Replace the router? Replace both? Try a Netgear router to go with the Netgear modem? Try a commercial router with better tech support? We have voice service as part of our Comcast package, and at present, they offer only TWO modems compatible with that . . . both by Netgear.
--- rant off ---

Thanks to all who have tried to help. I'm hopeful that changing the DHCP query frequency to "Aggressive mode" did indeed help, but there is no way to know for sure. Maybe disconnect the cable for a moment and see what happens?
 

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