Using Fios Router for internet is currently so painfully slow!

[qizhigang]

I have been experiencing a very painful slowness using the Fios router to connect to the internet. The reason is that if I bypass the router and directly connect my PC to the wall ethernet jack that coming from the basement, the speed is super fast as before like about a couple weeks ago! If I connect the router to the wall jack and connect my PC to the router, the YouTube videos I'm watching become just constantly buffering and won't be even watchable. Even if the video plays again after frequent buffering, the video quality would be so poor! The slowness happens when browsing or sending emails thru GMail; sometimes sending a simple email will take me to try twice! To open an email takes like 10 seconds each time which in the past just instantly! I asked Verizon to send me a new Router (model G3100) but it's still exactly the same slowness. I have Gigabit Fios Internet service with Verizon and as said it had been so fast and smooth until about a couple weeks ago (at least before 7/1/2022) but all of a sudden it became so slow now! By the way, the WiFi connection from the Router has been fine though. I have a laptop using the WiFi connection can watch YouTube videos very smoothly but I mainly use my desktop for everything which is connected to the router using CAT5e cable which the internet is so slow now! Anyone experiencing the same? Should I call Verizon again for this?

[dexman]

Has Verizon switched you to IPv6? 🤔

[qizhigang]

Not sure if Verizon switched my service to IPv6 or not, at least no notification or email from Verizon about it.

Btw, the internet is so slow that replying to your post took several minutes!

[dexman]

When logged into the G3100 as the Administrator, there is a screen that indicates if IPv6 is active. It might be worth checking.

If it is active, and if the computer has an Intel NIC, then a workaround offered by Cang_Household should get the speed back up again.

[qizhigang]

I logged on as admin and see Broadband IPv6 as green connected and I see IPv6 address all over place on the admin page. Can you post the link of the workaround that Cang_Household offered, I will then give it a shot? Thanks a lot!

[dexman]

Cang_Household posted the following link to Intel's website. The page discusses a known issue with Intel NICs. 🙂

Disabling TCP-IPv6 Checksum Offload Capability with Intel® 1/10 GbE Controllers

[qizhigang]

It IS the IPv6 problem! However, although my desktop has Intel 82579LM Gigabit NIC, the advanced tab of the NIC doesn't have any of the  TCP Checksum Offload entries listed, see the attached screenshot.  But I disabled the IPv6 at the NIC level, then the speed back to normal now and super fast again! However, this means I will not be able to visit those IPv6 websites, right?

[Cang_Household · Accepted solution]

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@qizhigang wrote:

However, this means I will not be able to visit those IPv6 websites, right?

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That's correct. Unless you have a IPv4 -> IPv6 NAT in between your computer and the IPv6-only websites, you cannot access them. I need to confirm whether Fios routers have this feature.

Your NIC is listed as the second affected product in the Intel technical brief. Not seeing the TCP Checksum Offload options is a sign of an outdated driver. Updating the driver won't fix the IPv6 issue as Checksum Offload feature is hardware based. To solve this issue once and for all, you need to replace the NIC with a different brand. Virtually all Intel 1G and 10G NICs are affected, as well as 2.5G NICs. Furthermore, disabling TCP Checksum Offload on 2.5G NIC won't remedy the issue.

[qizhigang]

😭 😭 Thank you so much, @Cang_Household, for the insight and prompt response!! Appreciate it! Guess my only option now is to try to get another NIC (non-Intel) inside my desktop. My Dell desktop is indeed quite old and I think the NIC is a build-in on the motherboard. Will try to see if I can find an open PCIe slot to fit a new NIC. Thanks so much again! And yeah, pls confirm if Fios routers have an IPv4 -> IPv6 NAT feature. 🙏

[qizhigang]

Just an update... I bought a NIC (not Intel brand) from Amazon as below. I installed it on an empty PCIe slot and installed the driver. Now I can use this Ethernet port with both IPv4 and IPv6 enabled and still have super fast speed now. Videos on YouTube never buffering anymore, even 4K! I only have Gigabit Fios services so 8K video will be really choppy but I won't be needing to watch 8K on my small monitor after all. Issues totally resolved! Thanks a lot for all the help from this forum! Appreciate it!

Cudy 2.5Gbps PCI Express Network Adapter, 2.5GBase-T PCIe Card, RTL8125 NIC