help Internet speed & packet loss issues!

[Trucido]

Hello, so to start off I would like to say that I pay for Gigabyte internet for speeds around a gig.
So up until yesterday my internet would run like usual, about 300-600 Mbps, however yesterday that changed to about 15 Mbps for a reason of which I don't know.

Also not the main problem but I have constant packet loss and fluctuation issues.

A few things for context, I will be comparing speeds from my computer with speeds from my iPhone 6s. (I know I should be using Ethernet for my pc but for reasons I can't explain I can't.)
Also my specs;
Windows 10 x64 | Newest version

Ryzen 5 3600
TUF Gaming x570-Plus (WI-FI) | I use the included wifi adaptor which Is seen on the packaging for the product
Nvidia GTX 1060 6gb
Corsair Vengeance 16gb (x2) DDR4

So on my pc as I previously stated I am only getting ~15 Mbps where as on my phone I get around ~200 with it placed in the exact same position as the adaptor.
This leads me to believe that it is a hardware issue on my pc. Furthermore all my software drivers and firmware are up to date.

AC-9260 Wi-Fi 5 (802.11ac) is what says comes with the motherboard in the adaptor which should be able to handle speeds way faster than 15 Mbps

Also something else of note which is probably unrelated but worth mentioning, the day before my connection to the router went haywire I got a new headset.
Plugged it in and it worked fine but after I shut down my pc for the day and rebooted it the next is when I started having issues.

I just used windows diagnose tool on the adapter through "Network Connections" on the control panel and it says "Your computer appears to be correctly configured, but this device or resource (DNS server) is not responding" Don't know if that will help anyone solve that but the more info the better. This only happens occasionally.

 

I have already installed and reinstalled the newest drivers and updates manually from the manufactures.