How to figure the cause of slow internet speed on one device connected with wifi?

[Tickler]

At first I was thinking that there is problem with service provider because I was getting correct speed at about 300 Mbps until a week ago but then the speed dropped and keeps fluctuating between 20 - 25 Mbps on my main computer running Windows 10. When I tried connecting my Wifi to other desktops, laptops and smartphones, they are all getting the 300Mbps which means the problem is on my one computer only but I can't figure out what. Any help Appreciated.

[AlienForce1]

That`s usualy a  wrong WiFi driver - you should install manufacturer`s driver  instead of Microsoft`s .

[DLord]

Damaged wifi card, incorrect driver, or wrong settings.

Shouldn't be difficult to diagnose.  If you have a USB wifi adapter it makes it easy to find a problem much quicker (eliminating the possible settings part of the problem).

[Kalju]

If this happens with the same WiFi adapter, there is probably a problem with the WiFi settings on your computer.
Of course, you should use 5GHz Wifi if You want to get more than 100Mbps, because if you use 2.4GHz (or at least a frequency lower than 5GHz), your maximum speed is 100Mbps.
Different computers have slightly different settings, so it is recommended that you use a dedicated program, such as IObit Internet Booster (Advanced SystemCare Pro must be installed and activated to install this tool), or if you are a professional, open the WiFi settings (for example, from the control panel) and do it manually.
From Control Panel find Network and Internet => Network and Sharing Center and now find Connections => WiFi => twice click on it and if new window opens, click on properties (bottom) and then must open new window, there find configure under WiFi Properties.
More can't recommend, because it depends what WiFi adapter and What computer You have. What selections You have, may be very different.

 

PS. If some days ago everything was good, then not possible, there is wrong or bad network card or wrong driver. (of course if the driver wasn't updated just before the problem appears, remember the latest driver is not always the best).

[Tickler]

Alright so uninstalling the drivers and then restarting the computer fixed the issue. Thanks.