[SOLVED] WiFi: Recent Degradation of speed/performance - Wireless Adapter Issue?

[thunderbolt36]

Wireless adapter: D-Link DWA-525 Wireless N 150 Desktop PCI Adapter
WiFi Router: TP-Link C6 AC1200 Router

I have been using my current WiFi adapter on my PC for over 9 years now. Over the past few months there has been a significant degradation in WiFi speeds compared to the speeds from last year, especially slow download speeds while upload used to be fine. Over the last few days, both the upload and download speed has significantly reduced further to unbearable speeds.
Other mobile devices and laptops connected to the same router has full download and upload speeds all this time. This includes some devices which are 2.4GHz only, which still get the full speed as other 5GHz devices.
I am wondering if this issue is due to a dying WiFi adapter card which might need to be replaced? Or is there some other troubleshooting I could do before buying a new one?

Some 1+ years ago I started seeing some odd issues with the Wireless adapter such as it getting easily undetected in the OS (both Windows and Linux Mint). Sometimes a simple restart fixes it. Occasionally I need to remove the WiFi adapter from the motherboard and reseat it again to fix when it does not get fixed by a restart. This particular issue has reduced significantly over the last 6 months.
I have checked the drivers of the WiFi adapter and it has not had any updates released since quite a long time.

PC specs as requested below:
CPU: Intel Core i7 960
Motherboard: ASUS P6X58D-E
PSU: Seasonic SS-750KM3 X-Series 750W Modular Power Supply (4 years old; condition is quite good; no issues so far)
RAM: 3 x 8GB Corsair Vengeance DDR3
Hard Disk: Crucial MX500 SSD 500 GB (30 GB free)
Graphics Card: Zotac GTX 1060 6 GB
OS: Windows 10 20H2

yup, it's quite old and upgrade quite overdue. Hoping that this lasts me until hardware stocks and prices are back to normal. Fingers crossed.

 

[Ralston18]

Update your post to include full system hardware specs and OS information.

Include PSU: make, model, wattage, age (9 years?), condition?

Disk drive(s): make, model, capacity, how full?

It could well be a failing faltering WiFi adapter.

However, a failing faltering PSU will also create all sorts of problems.

Things you can do:

Use Task Manager and Resource Monitor to observe system performance. Use both tools but only one at a time.

You may be able to see what happens or changes when the WiFi speeds degrade.

Look in Reliability History and Event Viewer. Either one or both may be capturing some error codes, warnings, or even informational events that will correspond with loss of WiFi speeds.

Run the built-in Windows troubleshooters. The troubleshooters may find and fix something.

Look in the router's logs (if available and enabled). The router's logs may be capturing some error or relevant event.

This router?

https://static.tp-link.com/2020/202007/20200727/1910012811_Archer A6&Archer C6_UG.pdf

Reference physically numbered Page 89.

 

[thunderbolt36]

Update your post to include full system hardware specs and OS information.

Include PSU: make, model, wattage, age (9 years?), condition?

Disk drive(s): make, model, capacity, how full?

However, a failing faltering PSU will also create all sorts of problems.

Updated the specs and details in above post.

Things you can do:

Use Task Manager and Resource Monitor to observe system performance. Use both tools but only one at a time.

You may be able to see what happens or changes when the WiFi speeds degrade.

The WiFi speed has been consistently slow since the last 2-3 days (for both upload and download).
Did check the Resource Monitor/Task Manager and did not notice anything unusual, or unexpected programs running or using up the network bandwidth.

Look in Reliability History and Event Viewer. Either one or both may be capturing some error codes, warnings, or even informational events that will correspond with loss of WiFi speeds.

Run the built-in Windows troubleshooters. The troubleshooters may find and fix something.

Nothing in the Reliability History for this month except for some "Windows not properly shutdown".
Similarly in Event Viewer for last few days. If there is any particular filter I need to use, I could try that.

Troubleshooter for the WiFi Network Adapter did not find anything.

Look in the router's logs (if available and enabled). The router's logs may be capturing some error or relevant event.

This router?

https://static.tp-link.com/2020/202007/20200727/1910012811_Archer A6&Archer C6_UG.pdf

Reference physically numbered Page 89.

Logs are enabled, but no items at warning level, or error or above.

That pdf link does not open for me due to region differences. This is the router page: https://www.tp-link.com/in/home-networking/wifi-router/archer-c6/v2/

 

[Ralston18]

Two things of immediate note:

1.) Disk space at 94% capacity (470 GB). Generally disk capacity should not be filled beyond 70-80% of capacity. There are different thoughts on the value be 94% full is going to become problematic.

Do be sure to keep all important files backed up at least 2x to locations off of the current host computer. Verify that the backups are recoverable and readable.

Use Disk Clean to free up more space.

2.) PSU: May appear to be good but 4 years old may well be pushing the designed in EOL (End of Life). Remember that PSUs provide 3, 5, and 12 volts to varying system components. It only takes one faltering or failing voltage to create problems.

Those improper shutdowns by Windows that are now being flagged in Reliability History and Event Viewer may be another forewarning.

= = = = What you can do = == =

Backup, backup, backup.

If at all possible use an Ethernet connection between computer and router. Determine if the network performance improves.

Do you notice the D-Link DWA-525 Wireless N 150 Desktop PCI Adapter getting hot during network use? Feel the outside back plate before booting up. Then as WiFi is continually being used carefully feel to sense if the plate is getting warm, really warm, or even hot. The latter two may indicate a problem.

Another thought: check around - there may be an antenna extension cable available. If so, install the extension cable. Moving the antenna up and away from the computer's back may help improve reception and, more importantly, transmission.

Borrow a known working USB wireless network adapter. Disable/remove the current wireless network and install the borrowed USB wireless network adapter. Manually download, install, and configure the USB wireless network adapter drivers as applicable for the host computer and your network.

Determine if wireless performance improves.

 

[thunderbolt36]

I actually did verify the speeds using Ethernet cable directly from the router and I am able to get the full speed as the other devices. So, it is just over WiFi where the speeds are very slow.
But it is not practical for me to keep the Ethernet cable connected at all times, which is why I am looking to fix the WiFi issues or replace the WiFi adapter.

Regarding your other points. I will see if I can try them out. Does not seem possible to borrow a working USB Wireless network adapter from anyone.