Hello,

I am having an issue with my TP-Link TL-WN781ND (PCI-E, 150Mbps, 2.4GHz) wireless adapter. The problem started recently, and I have tried several troubleshooting steps, but the WiFi still won’t connect reliably.

Symptoms:

My adapter can see my 2.4GHz network with full signal strength (5 bars).
When I attempt to connect, the signal drops to 0–1 bar and the connection fails.
The network sometimes disappears from the list entirely when trying to join.
Other devices (phones, laptops) connect to the same network without issues.
Ethernet connection works fine on the same PC.

What I have tried so far:

Uninstalled the TP-Link drivers completely and reinstalled them from scratch.
Enabled 802.11d in the advanced settings.
Set Wireless Mode to 802.11b/g/n (Auto).
Set Bandwidth to 20MHz only.
Disabled power saving options in Device Manager.
Checked PCI-E slot and antenna connections (everything seems physically secure).

Adapter advanced settings:

802.11d = On
Antenna Diversity = Auto
Bandwidth = 20MHz only
Wireless Mode = Auto (b/g/n)
Roaming Sensitivity Level = Low
Preamble Type = Long & Short
Wake on Magic Packet / Pattern Match = On

Environment:

Windows 11 (latest updates installed)
Router: Telia provided, 2.4GHz network visible and working on other devices
Adapter installed in desktop PC

It seems the adapter can see the network but cannot successfully join. I am wondering if this is a driver compatibility issue, hardware problem, or some setting I might have missed.

Does anyone have advice on how to fix this issue, or should I consider replacing the adapter with a modern PCI-E WiFi 6/6E card?

Thank you in advance for your help!