FS#3373 - IPV6 flow offload broken

[openwrt-bot]

graphine:

Enabling this option makes the ipv6 connection unstable.

Example: connecting to #openwrt-devel from hexchat (Ubuntu) makes you constantly disconnect.
Disabling flow offload makes the connection stable.

[openwrt-bot]

netprince:

I can confirm, using -j FLOWOFFLOAD from ip6tables causes ipv6 connections to stall after a few minutes.

[openwrt-bot]

netprince:

Just another datapoint, using the exact same configuration for each build. This was tested using a Xiaomi Mi Router 3G. This occurs with and without hardware offload enabled.

A build of OpenWrt 19.07-SNAPSHOT, r11285-11f4918ebb (dated 20210125), offloading works great.

A build of OpenWrt SNAPSHOT, r15599-37752336bd (dated 20210125), ipv6 connections stall after being idle for a while. (switching back and forth between apps on a phone for example)

When the connection stalls, everything in the app (on my phone) just hangs for about 8-10 seconds before finally coming back to life.

[openwrt-bot]

hacc1225:

Tested on ath79 (TP-Link Archer C7 v2) with the same issues.

[openwrt-bot]

hacc1225:

When -j FLOWOFFLOAD is enable, the IPv6 packet loss rate is as high as 50%.
Build the image with commit ddab795

[openwrt-bot]

ijoda:

I'm still seeing this issue in OpenWrt 21.02.0-rc1 r16046-59980f7aaf (netgear r7800). I'd be happy to help diagnose this if given some assistance in how to best track it down.

[openwrt-bot]

aag:

confirm this exact issue still happening on r16708-e7249669d2 on r7800

[openwrt-bot]

kkeijzer:

I also have this issue on a WDR4300 with 21.02.0-rc3. Flow offloading was working fine before, with 19.07.7. Connections break completely after a while, all kinds of elements on web pages are not loaded, and so on.

[openwrt-bot]

andybotting:

Took me a week before I discovered this issue, and I find this bug report just after I add a new topic to the forum https://forum.openwrt.org/t/21-02-0-rc3-losing-ipv6-packets-when-flow-offloading-1/100575

In the mean time, I've just added this line to /etc/firewall.user
ip6tables -D FORWARD -m comment --comment "!fw3: Traffic offloading" -m conntrack --ctstate RELATED,ESTABLISHED -j FLOWOFFLOAD --hw

[openwrt-bot]

farmergreg:

I think I may have a similar issue with IPv4 and flow offloading turned on. Idle ssh connections drop relatively quickly when offloading is enabled. When offloading is turned off, they stay connected indefinately. Please see issue #3759 where I have documented the problems that I have had.

[openwrt-bot]

farmergreg:

I meant to write please see issue #3759. Thanks!

[openwrt-bot]

bohdan-s:

Hi, I have confirm my bug FS#3973 is linked to this bug. Disabling offloading or IPv6 resolves the issue. But when both are enabled this bug is observed.

[openwrt-bot]

Shine-:

OK, seriously. You released 21.02 today. With this bug. I updated. It - well - STOPPED WORKING. You know, most major websites, like, Google. Facebook. Ebay. Are using IPv6. And you are releasing a new major release of OpenWRT that stops supporting IPv6. Wow. Hello? I mean, yes, offloading is disabled by default. But every 19.07 user has it turned on, because OpenWRT is painfully slow without. And now you break it? And nevertheless release the broken version as a new major release? Again, wow. Wow.

[openwrt-bot]

cuviper:

The 21.02 release has not been announced yet, but I expect this will be a known issue in the release notes, just as it was in rc4. The developers decided not to let this be an indefinite blocker, as the release is already very late. It sounds like this will still be investigated for a point release though.

[openwrt-bot]

fda:

I have multiple vlans and separate ULAs on every interface. odhcpd announces every subnet to every vlan!
Now i noticed this bug is also gone with disabled sw-offloading

[openwrt-bot]

User_nikolad:

Archer C7-V2. Problem confirmed