Internet speed is slow on my PC but not on my WiFi?

[Louie999]

This is quite a weird situation. My standard download speed is 5 Mbps but when I test it using SpeedTest, I only get around 2-3.8 Mbps on my PC. However, when I run the test on my phone using the WiFi then the speed is normal (4.8-5 Mbps). I had my internet connection examined by my ISP, and after quite a lot of troubleshooting, it seems that the problem really isn't the internet connection itself but most likely my PC.

But what could cause this? My PC isn't old or anything, nor is it bad. How can I fix this problem?

Edit: Just in case, here are some extra details about my PC. (If it means anything):
OS: Windows 10 - 64 bit
Processor: Intel Core i5-7400 3.0 GHz
GPU: GTX 1050 Ti
RAM: 8 GB

 

[Louie999]

What are you using to actually connect to the internet. Ethernet or WiFi.

For my PC? Ethernet.

 

[smorizio]

make sure to install newest intel chipset and ethernet drivers for you mb.

 

[Louie999]

I think I just managed to fix it myself lol. I ran an antivirus scan and it appears that I had some adware/malware. My internet speed is now back to its normal speed after those things got deleted.