Asus RT-AC88U dropping IPv6 connections

[NSNE]

Instead of just opening a thread to pose a problem, I'm also proposing a possible solution that I hope will help others who are pulling their hair out over their RT-AC88U (or any other Asus router) inexplicably dropping IPv6 connections.

After performing the most recent firmware update (3.0.0.4.380.4180, released 12/21/2016), I noticed that the self-populated fields on the router's IPv6 page were blank despite this feature being enabled. I wasn't sure how long it had been like this; I only noticed it because I was poking around after the firmware update.

I tried disabling and re-enabling IPv6. I tried rebooting the router. I tried toggling a whole host of settings on and off (UPnP, IPv6 firewall, etc.). I rebooted my modem countless times. At wit's end, I even did a factory reset of the router.

A-ha! The factory reset restored IPv6. But only temporarily. As soon as my LAN clients started reconnecting, the IPv6 fields went blank again.

So I started looking at my clients, and one in particular stood out: an Apple AirPort Express, which recently got a firmware update of its own (7.6.8). For some reason, it was appearing as a single device with two IP addresses. Even after I assigned it a static IP and bound its MAC address to that IP, it still ended up snagging two IP addresses for itself. Odd, right?

I then pulled the AEx off the network, rebooted the RT-AC88U, and immediately IPv6 returned. Six hours later, IPv6 is still there, although the AEx remains unplugged and off-network (and therefore unusable).

The tl;dr is that my ethernet-connected Apple AirPort Express in a bridge AirPlay mode and no other functions enabled was singlehandedly responsible for my RT-AC88U losing its IPv6 connection. I still don't know why. Its IPv6 had been set to "Automatic" and should simply have been assigned an address by the router's DHCP. There must be some sort of conflict or bug.

The next step in my troubleshooting will be to reconnect the AEx but keep its IPv6 in link local mode.

At any rate, I know that dropped IPv6 connections aren't uncommon to Asus routers, and I wanted to share my experience to save some other poor sap hours of Googling and trawling through forums.

 

[SMSparky]

Instead of just opening a thread to pose a problem, I'm also proposing a possible solution that I hope will help others who are pulling their hair out over their RT-AC88U (or any other Asus router) inexplicably dropping IPv6 connections.

After performing the most recent firmware update (3.0.0.4.380.4180, released 12/21/2016), I noticed that the self-populated fields on the router's IPv6 page were blank despite this feature being enabled. I wasn't sure how long it had been like this; I only noticed it because I was poking around after the firmware update.

I tried disabling and re-enabling IPv6. I tried rebooting the router. I tried toggling a whole host of settings on and off (UPnP, IPv6 firewall, etc.). I rebooted my modem countless times. At wit's end, I even did a factory reset of the router.

A-ha! The factory reset restored IPv6. But only temporarily. As soon as my LAN clients started reconnecting, the IPv6 fields went blank again.

So I started looking at my clients, and one in particular stood out: an Apple AirPort Express, which recently got a firmware update of its own (7.6.8). For some reason, it was appearing as a single device with two IP addresses. Even after I assigned it a static IP and bound its MAC address to that IP, it still ended up snagging two IP addresses for itself. Odd, right?

I then pulled the AEx off the network, rebooted the RT-AC88U, and immediately IPv6 returned. Six hours later, IPv6 is still there, although the AEx remains unplugged and off-network (and therefore unusable).

The tl;dr is that my ethernet-connected Apple AirPort Express in a bridge AirPlay mode and no other functions enabled was singlehandedly responsible for my RT-AC88U losing its IPv6 connection. I still don't know why. Its IPv6 had been set to "Automatic" and should simply have been assigned an address by the router's DHCP. There must be some sort of conflict or bug.

The next step in my troubleshooting will be to reconnect the AEx but keep its IPv6 in link local mode.

At any rate, I know that dropped IPv6 connections aren't uncommon to Asus routers, and I wanted to share my experience to save some other poor sap hours of Googling and trawling through forums.

I'm glad I'm not the only one with IPV6 problems with this router. I spent countless hours trying to get it to work and gave in to calling Asus tech support. After some initial troubleshooting they had me replace the router, so I did only to have the same problems again. Then they had be do a firmware restoration on the replacement router only to have the same problems. I don't usually give up on troubleshooting, but found i was spending far too much time troubleshooting what appears to be a flaw in their firmware. My D-Link router had no issues with IPV6 so i ended up putting it back into service, and happy that i did. I only tried Asus because of all the rave reviews and that it has 8 GIG ports which is rare on home based routers.
By the way, here's the kicker a few days ago i receive a email from Asus that they found a solution - to install the latest firmware version 4180. Seems it didn't solve your problem and most likely would not have solved mine. Many people don't even know what IPV6 is. They plug in the router and get an internet connection and their happy. I hope Asus fixes this issue they have one of the best GUI interfaces with tons of customization options which is really helpful.

 

[NSNE]

Well, my AirPort Express has been back online for several days with IPv6 set to Link Local. This has prevented any further IPv6 errors so far.

Although I'm aware that Asus' IPv6 implementation has been a bit flaky for some users, in this case it's the AirPort Express that seems to be causing the issues. For some unknown reason, it's still grabbing two IP addresses for itself, which appears to be a long-running and common occurrence.

 

[Gregory Phillips]

I have the same problem and I'm running the latest firmware 3.0.0.4.380_7266. I have IPV6 set to native and on the firewall page general settings I have icmp enabled. I can keep an IPV6 address for around an hour and then it will go away. Initally when setup the router it was disabled but would still issue address for a short period and then just stop. I've emailed tech support but they weren't much help besides having me hard reset the router which is when I started receiving IPV6 addresses to clients with the IPV6 set to disabled. I'm very close to trying merlin's latest version to see if behavior improves.

 

[SMSparky]

I have the same problem and I'm running the latest firmware 3.0.0.4.380_7266. I have IPV6 set to native and on the firewall page general settings I have icmp enabled. I can keep an IPV6 address for around an hour and then it will go away. Initally when setup the router it was disabled but would still issue address for a short period and then just stop. I've emailed tech support but they weren't much help besides having me hard reset the router which is when I started receiving IPV6 addresses to clients with the IPV6 set to disabled. I'm very close to trying merlin's latest version to see if behavior improves.

I hope you get it working and if so please let us know. I really like this router but gave up on it because of this IPV6 issue.

 

[Gregory Phillips]

Gentlemen I flashed to AsusWRT-Merlin 380.65_2 firmware this morning and this is what has happened for me.

Edit: About an hour after I posted that I lost my IPV6 connection. When I rebooted it returned and as long as I have multiple clients attached it stays. There must be some protocol missing in the router that needs to contact the Comcast server to keep it alive. When I connect a pc directly to my cable modem the IPV6 connection stays put.

 

[NSNE]

After flashing to .7266 back in February, I noticed the IPv6 drops too. Same problem as everyone else is having, that is, the 88U obtains an IPv6 address after both the modem and router are rebooted, then loses it again in about an hour.

In the past I used to be able to run the command service restart_dhcp6c, and that would restore IPv6 functionality, at least temporarily. Now it doesn't.

I've reported this issue probably a dozen times to Asus.

I swapped out the 88U for a Netgear router, which has no trouble holding onto the IPv6 address. But I prefer the Asus on account of the GUI and the QoS options. And VPN (which is on the Asus, not the Netgear) is going to be a must-have now that ISPs can sell our browsing data.

 

[Gregory Phillips]

Folks I flashed to AsusWRT-Merlin 380.65_2 yesterday morning which you can find on his main download page for all routers he services. Once I flashed it would behave the same way as stock but when I powered down completely to drain the unit and then rebooted my RT-AC88U immediately obtained an IPv6 address and began issuing them to all attached clients. It has been up a day and a half so far without any disconnects. I forwarded what I've discovered to Asus technical support including the fact that I had to use 3rd party Merlin firmware to accomplish this functionality.
https://asuswrt.lostrealm.ca/download

 

[Gregory Phillips]

Just an update but this morning without warning my 88u dropped the IPv6 address sending me back to IPv4. I have the my ip address data showing how it worked right for about 45 hours so I'm wondering if moving to the 380.65_4 firmware would have any effect on this problem.

Edit: I just flashed to 380.66 alpha to see if anything improves for me. I wish we could nail down the root cause and fix it once and for all.

 

[Gregory Phillips]

380.66 alpha didn't work for me which began an entire series of reflashes trying to find a firmware that would give me a stable IPv6 connection. Neither 3341 or 7266 would give me an IPv6 connection nor would any of the Merlin 380.64's so I flashed up to 380.65 for the first time which immediately obtained an IPv6 connection. I'm going to keep an eye on this and see how long it can keep it.

 

[Gregory Phillips]

In a latch ditch effort I replaced the cheap Ethernet cable between the router and modem with a cat 6 shielded line to see if it makes any difference. I'm running Merlin 380.62_2 firmware because it has worked the best for me so far. If I cannot retain my IPv6 address I'll replace the cable modem with a docsis 3.1 model on Comcast's approved list.

 

[phonos]

In a latch ditch effort I replaced the cheap Ethernet cable between the router and modem with a cat 6 shielded line to see if it makes any difference. I'm running Merlin 380.62_2 firmware because it has worked the best for me so far. If I cannot retain my IPv6 address I'll replace the cable modem with a docsis 3.1 model on Comcast's approved list.

Any update on this? I've been missing IPv6 for months now after ASUS firmware updates. I've contacted ASUS support several times and they keep putting me into this "we'll follow up in 48 hours and two weeks later nada. I'm running the SB6190 modem but IPv6 works fine when bypasing the ASUS router.

 

[Gregory Phillips]

I replaced the modem with a Netgear CM1000 DOCSIS 3.1 which will be on Comcast's approved list for a long time. Since that post I've tried both Merlin and Asus firmware as I have also been going back and forth with Asus tech support which has done next to nothing except tell me to do the same junk over and over again. Even the new 7378 will not get an IPv6 address from Comcast via DHCP.

I am currently running Merlin 380.66 beta1 firmware which will get an IPv6 address via DHCP from Comcast each and every time. I am also using the reboot scheduler to have the router come up fresh every other morning before we get up to help with stability.

I'm running the SB6190 modem but IPv6 works fine when bypasing the ASUS router.

Get your ISP's IPv6 DNS server addresses and then go to the router IPv6 page and go down to DNS settings and set connect to DNS server automatically to no. Then manually enter your ISP's IPv6 DNS server address and click apply at the bottom. It should connect to them and start providing you with IPv6 addresses. I keep complaining to tech support because Merlin's firmware can DHCP those addresses from Comcast each time and the stock cannot.

This is a list of Comcast's DNS servers if you need them.
https://dnschecker.org/dns/United-States-of-America/Comcast

 

[gaff]

I had a similar issue, I noticed that my host was able to initially get an ipv6 address, but would drop it after 10 minutes.

Using wireshark I found that my router was responding to Router Solicitation ICMP6 messages, but wasn't sending periodic Router Advertisement messages.

It seems that disabling (and restarting) then enabling (and restarting) the "Enable Router Advertisement" setting caused the router to resume these messages. I still need to experiment to see what happens if I power-cycle the router, but it's a step forward.

Some more details here: https://superuser.com/questions/137...0-minutes?noredirect=1#comment2074817_1376664

 

[phatcat cane]

Having similar issues with the Blue Core. IPv6 seems to stay up for about a day before getting unstable and ultimately dropping. Clients are having connectivity issues as well on IPv6 or dual stack. Turning off IPv6 seems to help stability. Sounds like a bug in the code and maybe I'll retry it after the next update.

 

[Gregory Phillips]

Sorry to hear that you guys are still having issues with IPv6 as Asus fixed the firmware last year and I haven't had the issue recur since.

 

[phatcat cane]

I may have found out what the problem is. Still testing but so far IPv6 has remained active.

I use a Trendnet Wireless Bridge that has a few devices in a closet. I had enabled it for IPv6. I restarted IPv6 on the Asus Blue Core after the last signature update. I checked the Trendnet and had it reconnect to the DHCPv6 server. Sure enough, 10 minutes or so later, IPv6 devices started having issues and I had to reset the router. I have since changed the Trendnet to a static IPv6 address and this seems to have fixed the problem.

I will continue to monitor and report back. It's extremely difficult to troubleshoot though because there isn't much information in the Asus logs and the DHCPv6 server doesn't appear to show more than 4 clients.