Wifi really slow on PC only

[PC108]

I just bought a PC from PCS with the following specs:

Case
CORSAIR CARBIDE SERIES™ 275Q QUIET CASE
Processor (CPU)
AMD Ryzen 5 3600 Six Core CPU (3.6GHz-4.2GHz/36MB CACHE/AM4)
Motherboard
ASUS® PRIME B450-PLUS (DDR4, USB 3.1, 6Gb/s) - RGB Ready!
Memory (RAM)
16GB Corsair VENGEANCE DDR4 3200MHz (2 x 8GB)
Graphics Card
4GB NVIDIA GEFORCE GTX 1650 SUPER - HDMI
1st Storage Drive
1TB SEAGATE BARRACUDA SATA-III 3.5" HDD, 6GB/s, 7200RPM, 64MB CACHE
1st M.2 SSD Drive
250GB SAMSUNG 970 EVO PLUS M.2, PCIe NVMe (up to 3500MB/R, 2300MB/W)
Power Supply
CORSAIR 550W TXm SERIES™ SEMI-MODULAR 80 PLUS® GOLD, ULTRA QUIET
Power Cable
1 x 1 Metre UK Power Cable (Kettle Lead)
Processor Cooling
STANDARD AMD CPU COOLER
Thermal Paste
STANDARD THERMAL PASTE FOR SUFFICIENT COOLING
Sound Card
Creative Sound Blaster® Audigy Rx
Wireless/Wired Networking
WIRELESS INTEL® Wi-Fi 6 AX200 2,400Mbps/5GHz, 300Mbps/2.4GHz PCI-E CARD + BT 5.0
USB/Thunderbolt Options
MIN. 2 x USB 3.0 & 2 x USB 2.0 PORTS @ BACK PANEL + MIN. 2 FRONT PORTS
Operating System
Windows 10 Home 64 Bit - inc. Single Licence
Operating System Language
United Kingdom - English Language
Windows Recovery Media
Windows 10 Multi-Language Recovery Image - Unlimited Downloads from Online Account
Office Software
FREE 30 Day Trial of Microsoft® Office® 365 (Operating System Required)
Anti-Virus
BullGuard™ Internet Security - Free 90 Day License inc. Gamer Mode
Browser
Microsoft® Edge (Windows 10 Only)
Warranty
3 Year Standard Warranty (1 Month Collect & Return, 1 Year Parts, 3 Year Labour)
Delivery
STANDARD INSURED DELIVERY TO UK MAINLAND (MON-FRI)
Build Time
Standard Build - Approximately 10 to 12 working days
Promotional Item
Get 3 Months of XBOX Game Pass for PC w/ select AMD Ryzen CPUs
Welcome Book
PCSpecialist Welcome Book - United Kingdom & Republic of Ireland
Logo Branding
PCSpecialist Logo

Over the last couple of days I've noticed the internet is really slow. This may also have been from the start but only recently I started downloading larger files. This is the speed test result:

For reference this is the same speed test on my phone:

Any ideas what to do? I have attached the antenna as follows:

 

[ubuysa]

Generally the best first test you can do is to move the PC physically close to the router and use a cable to attach the PC. That will show whether the speed problem is a WiFi issue or something deeper.

Assuming it's fine when cable attached try the WiFi when physically close. If it's still poor go into Device Manager and in the Network Adapters section right-click on your WiFi card and select 'Uninstall', if asked to delete the driver answer 'Yes'. Now reboot and then go into Windows Update and 'search for updates', Windows should find and install the best driver for your WiFi card. See how it is then close to the router...