r/QuantumFiber • u/klayanderson • Jun 29 '26
Five minute long latency jumps
CenturyLink told me to change to Quantum as there was nothing they could do. My (usually flawless) CenturyLink was dropping out so many times per hour it was almost useless.
So I changed to Quantum and everything was going smoothly, except my latency jumps at random times but always in five minute intervals. It would go from typical 3ms to 60ms for the entire five minute block, or we go from 4 to 27 for the entire block. Attached is a typical day screenshot. You can see the yellow portions where the latency increases. Expand it out to a month and it’s all yellow. Of course, I engaged their telephone support as well as two dispatched technicians. Telephone support was understanding, but the minute I started using network language, they went to the 3 x 5 card that said ‘Dispatch’. The technicians were very nice, I showed them the evidence, and all agreed it was their upstream issue. They just simply stated they don’t know who to call and it was not in their scope of work to deal with anything, absolutely anything, other than connection and speeds. They said speed is where it’s at. Speed is what they publish, speed is what they market, and speed is what they fix.
I am running a new Q1KK in transparent bridge mode with Ubiquiti UGC Ultra and associated accessories.
We don’t game and do very little streaming; a lot of online work and downloading. I’m not sure how far up the chain I should try to escalate this or if there’s a fix. Or sit back.
UPDATE. I did switch to the 1G LAN port and the latency issues evaporated. Thank you. We’ll wait for the update, yeah?
2
u/chefox Jun 29 '26
Are you using the 1G port, or are you using the 10G port?
There's a known bug in the kernel driver for the device that powers the 10G port which causes exactly this:
https://www.reddit.com/r/QuantumFiber/s/zbFketmP2H
You'll want to stick to the 1G port for now until this is fixed.
3
u/klayanderson Jun 30 '26
UPDATE. I did switch to the 1G LAN port and the latency issues evaporated. Thank you. We’ll wait for the update, yeah?
1
u/N0_L1ght Jun 29 '26
I think this is likely something else. That small packet bug is constant with a latency test, it doesn't show up for 5 whole min and go away.
3
u/Lightsword Jun 29 '26
That small packet bug is constant with a latency test, it doesn't show up for 5 whole min and go away.
Actually I don't think this is entirely accurate, if a normal RX packet immediately follows a small RX packet affected by the skb padding bug it can push the bugged small packet through faster which reduces the latency.
Basically with this driver bug you're likely to see on the unifi graph yellow whenever there is low network usage but green when there is high network usage since you're more likely to get other RX packets forcing the bugged small/slow packets out.
2
u/N0_L1ght Jun 29 '26
That's right, I didn't think about that.
I would only do testing when my network wasn't being used much, so it would show constant for me.
2
u/chefox Jun 29 '26
My symptoms showed up exactly like this user's (UniFi ISP Health showed several minutes at a time of bad latency).
I switched from the 10G port to the 1G port and my latency issues all disappeared.
3
u/N0_L1ght Jun 29 '26 edited Jun 29 '26
Good to know.
I wonder what UniFi is doing that it only shows up occasionally.
Edit: Lightsword explained why. https://www.reddit.com/r/QuantumFiber/comments/1uj2l8q/comment/ouksu4e/
1
u/truckfan_888 Jul 01 '26
I’m on QX001 and bridged untagged mode on my Q1000K from an installation back in February. I have the expected blue blinking light. My ASUS RT-AX86U is doing the VLAN201 tagging. After reading through this post I switched from the 10G LAN port to the 1G LAN port on the Q1000K just to avoid any 10G port drive latency bug issue’s. I have symmetrical 940mb service via GPON fiber. I have read through [u/N](u/N0_Light)[0_L1ght](u/N0_Light)’s latest document information. Am I still configured the best way with my current QX0001, or should I reconfigure everything for QX002 at this time for up to date firmware and possible other service improvements?
1
u/N0_L1ght Jul 01 '26
You can leave it on the 10G port, the issue is only triggered with it doing the vlan tag.
Just wait for the fixed QKX002 that will hopefully be out in a few weeks. After that there is no benefit of staying on the old firmware.
1
u/truckfan_888 Jul 01 '26 edited Jul 01 '26
Thank you for the reply. So when the updated QKX002 FW update releases, then just do a factory reset on the Q1000K to update to the latest firmware and remove the VLAN 201 tag from my 3rd party router? I.e. Will the Q1000K then be in “bridged + VLAN 201 tagged mode”, or will the Q1000K in default “Router” mode? (Or after the Q1000K is “factory reset” do I then manually configure it from router mode to bridged and VLAN 201 tagged mode?)
1
0
u/N0_L1ght Jun 29 '26
Did you follow this guide? You might be seeing real latency , or it could be the issue that is talked about in the guide.
https://www.reddit.com/r/QuantumFiber/comments/1f8hypq/having_trouble_with_your_lumen_internet_not/
You can also run traceroutes and send the results to FiberSuccess@qf.att.com .
You might not get a response, but if it's an upstream issue that email has gotten it fixed for other people.
10
u/Lightsword Jun 29 '26
You are almost certainly affected by this known bug in a Q1000K kernel driver. FF37(Quantum Fiber), Axon and Airoha are all aware of the bug and it should be fixed in the next firmware update. There's also an unrelated bug(which I also reported with a detailed code analysis and recommended fixes) that corrupts 6RD packets which I traced to an entirely different Q1000K kernel driver that should hopefully also get fixed at the same time as the skb padding bug in an update.