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[SOLVED] What's causing randomly slow WiFi ?

Dec 28, 2020
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Hey all,

I've got a weird issue that I've never experienced before and it's driving me nuts. After I restart my PC my wifi adapter seems to work fine for a good 20 minutes or so. I've got Gigabit internet and for those 20 minutes I'm getting around 200 Mbps down and 100 Mbps up. Which is fine. However, after that 20 minutes, it drops, severely. I'm currently getting 2.5 mbps. I thought at first my wifi adapter went bad, so I bought a new one (PCI-e this time), however, the exact same thing happens. So I went as far as to reinstall windows and re-setup everything. The problem still happens!

I've also flushed the DNS and renewed my IP address.

I've got no idea how to fix it. When I run the command: netsh wlan show interfaces, it shows a Receive rate of 520 Mbps and a Transmit rate of 866.7 Mbps. However, like above, the speed test shows < 5 Mbps.

I'm hoping someone has had this problem before and can give me some help.

Please!
 
Solution
It is not likely the router because other devices work fine. Make sure you are testing using the same radio band. There really isn't much in a router you can change to affect only 1 machine and you would know if you had set it up.

The problem is you have pretty much elimianted all the possibilities. You have tried different nic cards, do you know if they run different chipsets..ie the drivers are not the same. Reinstalling windows should get rid of any strange software. At this point you almost have to start over try to see what was missed. Maybe boot a linux image from usb. This generally is good to test problems that are consistent. Having to wait 20 minutes could be a problem. Is it always the same, does it...
Hey all,

I've got a weird issue that I've never experienced before and it's driving me nuts. After I restart my PC my wifi adapter seems to work fine for a good 20 minutes or so. I've got Gigabit internet and for those 20 minutes I'm getting around 200 Mbps down and 100 Mbps up. Which is fine. However, after that 20 minutes, it drops, severely. I'm currently getting 2.5 mbps. I thought at first my wifi adapter went bad, so I bought a new one (PCI-e this time), however, the exact same thing happens. So I went as far as to reinstall windows and re-setup everything. The problem still happens!

I've also flushed the DNS and renewed my IP address.

I've got no idea how to fix it. When I run the command: netsh wlan show interfaces, it shows a Receive rate of 520 Mbps and a Transmit rate of 866.7 Mbps. However, like above, the speed test shows < 5 Mbps.

I'm hoping someone has had this problem before and can give me some help.

Please!
You really need to test with a wired connection from the same PC. You need to determine if it is ONLY a WIFI issue or a generic performance issue with that PC.
 
You really need to test with a wired connection from the same PC. You need to determine if it is ONLY a WIFI issue or a generic performance issue with that PC.


I I guess I forgot to mention that. Wired works fine and is consistent (no slowdowns). My Phone's wifi also works fine from the same room where the PC is located. Every other device in the house (including a laptop in the same room) works fine with wifi. It just seems to be my desktop pc. It's like something is limiting how much data it can receive/send via wifi, but I haven't found anything that's leading me to believe that's what is happening.

EDIT:
To add more information, rebooting the router doesn't have any effect. Once the slowdown occurs the only way to get another moment of highspeed is to restart my pc, which gives about 5-20 minutes of highspeed before it's slow again.
 
Last edited:
I I guess I forgot to mention that. Wired works fine and is consistent (no slowdowns). My Phone's wifi also works fine from the same room where the PC is located. Every other device in the house (including a laptop in the same room) works fine with wifi. It just seems to be my desktop pc. It's like something is limiting how much data it can receive/send via wifi, but I haven't found anything that's leading me to believe that's what is happening.

EDIT:
To add more information, rebooting the router doesn't have any effect. Once the slowdown occurs the only way to get another moment of highspeed is to restart my pc, which gives about 5-20 minutes of highspeed before it's slow again.
Have you checked your Windows Autotune -- https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/
It is also possible that your router is overheating with a high throughput WIFI stream. You could try pointing a fan at your router.
 
Have you checked your Windows Autotune -- https://www.ghacks.net/2016/08/05/windows-10-limiting-internet-speed/
It is also possible that your router is overheating with a high throughput WIFI stream. You could try pointing a fan at your router.

Unfortunately disabling autotune seemed to not have an effect (or made it slightly slower), so I've reset it back to normal. No dice there.

I don't think it's overheating, it doesn't seem warm at all, plus everything else still works and is able to get a pretty decent 100-200 Mbps out of it pretty consistently.


This issue really doesn't make much sense to me, I can't see anything that would cause this. I've dug through my router settings too, but it doesn't seem like anything there would cause this, but I'm unsure what most of the settings there do, so I'm hesitant to touch any of them.
 
Anyone experience anything like this?

I can post more info if needed. I still haven't been able to address it. No matter what I do the slowdown happens after 5 - 20 minutes of use. Only on this pc, and it's happened with 2 different network adapters. Like I mentioned above, it's like something is telling it to limit it's speed.

If it helps I've also run the netsh wlan show all command and both Receive Rate and Transmit Rate say 866.7 Mbps. The network card I'm currently using is: Intel(R) Wi-Fi 6 AX200 160MHz with the latest drivers.
 
It is not likely the router because other devices work fine. Make sure you are testing using the same radio band. There really isn't much in a router you can change to affect only 1 machine and you would know if you had set it up.

The problem is you have pretty much elimianted all the possibilities. You have tried different nic cards, do you know if they run different chipsets..ie the drivers are not the same. Reinstalling windows should get rid of any strange software. At this point you almost have to start over try to see what was missed. Maybe boot a linux image from usb. This generally is good to test problems that are consistent. Having to wait 20 minutes could be a problem. Is it always the same, does it matter if you let the machine sit totally idle or do you have to be doing stuff. Linux is going to be somewhat limited if you are doing something other than simple web surfing.

It almost has to be some software issue. It is highly unlikely 2 different nic cards would do the same thing. Then again it could be a wifi6 issue it is not as mature a product

...............So I wrote this and never hit post yesterday
 
Solution