Issue with DNS during peak network activity
Issue with DNS during peak network activity
Under heavy traffic the internet experiences 2-10 minute outages due to DNS resolution issues. This wasn’t a recurring problem before the incident, but it began after a rollback. Even after resetting the network, using different hardware, and flushing DNS, the issue persists. Disconnecting and reconnecting helps temporarily, though it remains frustrating. A permanent solution is needed.
This occurs because your ISP connection is less than your network's actual speed (for example, provisioned at 75Mbit but only offering 72Mbit). The best solution is to limit your network or PC usage to the bandwidth you're assigned (try a speed test and choose the lowest result). When bandwidth reaches full capacity—like uploading to YouTube—it stops DNS from functioning properly since requests aren't prioritized.
Have you explored the fundamental options? Consider using third-party DNS services such as Google DNS (4.4.4.4, 4.8.8.4) or Cloudflare DNS (1.1.1.1, 1.0.0.1).
I can adjust your router's DNS to 1.1.1.1 if you're comfortable with it. Your router normally gets DNS from DHCP through your ISP, which often has poor quality. You can change this setting in the router itself to Cloudflare (1.1.1.1), and it will then supply that via DHCP to all devices on your network. If you're unsure how to do this, you can follow the steps shown in the screenshot you provided. Consider using 1.1.1.1 as your preferred DNS and 8.8.8.8 as a backup. Check if this improves connectivity.
If your uplink connection is limited, it can't perform DNS queries. This usually occurs when the ISP provides a connection that's too low for the network's needs. I've noticed this consistently whenever uploads are done without capping the download speed. It doesn't depend on other activities you're running. If you upload a video to YouTube, your computer will freeze after a few seconds, no matter how fast your upload speed is. Microsoft allocates some bandwidth by default, but these defaults expect a stable LAN connection at 100mbps or higher, not a partial fraction of that. That restriction therefore doesn't apply. The person reporting this said it's due to heavy network usage. This would occur even with different DNS settings.
This situation is far from typical. I recall facing similar challenges with the internet in the early 2000s, around 2005. While overloading a link can slow downloads, it usually doesn’t bring down all outbound or incoming requests. I often upload files without any restrictions and never lose packets. That said, most DOCSIS connections include both upload and download channels. If your connection is outdated or your modem is very old, you might lack delegate lanes, which could affect downloads when uploading heavily—but that’s just speculation. In my experience over the past ten years or more, this hasn’t caused any problems. Additionally, your operating system doesn’t enforce rate limits, and Ethernet supports full-duplex communication, allowing both sending and receiving at maximum speed. Your internet browsing remains unaffected.
I believe I've never faced anything similar since dial-up, though I haven't had cable, only DSL and now fibre. It's possible this could happen if your router isn't functioning well—rate limiting wouldn't really matter then because the issue would be with the router itself. I'm not sure what you're referring to; ISPs usually provide a limited portion of their network capacity. Even at full speed, once you hit that limit, it behaves just like before. A connection that's fully used is still a fully used connection, and the same rules apply. It might be that your ISP is trying to send data faster than your line can handle, but this issue occurs at the network level regardless. Applying QoS at your end could help, but it shouldn't be required if you're already saturated.
On DSL, the ISP can provision various profiles. So they advertise 75/25 but the actual profile is this: Note that both 80.4 and 20.9 are not 88.3 and 22.5. My mistake, they currently offer: At any rate that doesn't change the scenario. So if you are uploading a video you youtube. This happens 100% of the time: Start upload, about 30 seconds or so in, everything on the computer, and network stops working. DNS requests time out, cached DNS (eg things still sitting in the web browser) time out if you reload them, ssh connections disconnect. Basically any time I upload a youtube video, I can do nothing else but use the internet on my phone instead. How I get around that is I explicitly rate limit chrome so that it can not upload at a rate more than provisioned. eg this way: However if I allow Davinci Resolve upload the video, the same thing happens, and the only way to hold back Davinci is by using third party software to rate limit network connections on the pc. The point I'm making here, is that what the OP is experiencing is pretty much the same thing I experience, and thus if they rate-limit the uplink to 90% of what the speed test tells them they have, not what the ISP tells them they have, not what the modem/router is provisioned at, the problem should go away. There is no other reason why consuming bandwidth causes the DNS to die. But not all network symptoms are the same problem. Like the other thing that comes to mind is there is device on the LAN side and it's sending out DHCP responses to try and knock the computer off the network, which would explain why the DNS times out, because you're temporarily connected to another device. But that is unlikely if the OP is only using their own computer on it.