WiFi problems can be caused by complex factors. When we're using/trying out an established product that's been in the market for years, then rarely is the problem due to its design. Since TP-Link's AX1800 router has been sold for years, it's reasonable to say your problems were not caused by the router or its design.

If you had described your problem here, and tried to diagnose what caused the problems, you may have realized it's a good product and kept it. Amazon gives 30 days to return things, so there isn't a reason to return something after only one day (unless you know it's defective/damaged).

Best of luck in finding a replacement router. If this router didn't work well in your environment, it's possible other routers will also have similar problems. For example, the following can cause the problems you saw (of intermittent device disconnections): many competing routers/devices operating on the same bands near your router (e.g. from neighbors), radio spectrum congestion, microwave ovens/other interfering devices running simultaneously, mis-configuration of devices, your mobile device may have been setup to "Auto join" several network SSIDs (causing it to automatically switch from one to another network when temporary interference caused the signal level to drop), etc.

Good luck.

  @HelpingOne 

The product was - TP-Link AX1800 Wi-Fi 6 Dual Antennas High Gain Wireless USB 3.0 Adapter (a USB wi-fi adapter for my desktop pc)

This adapter constantly disconnected, it would reconnect if I selected "connect" in windows but within minutes (sometimes seconds) it would disconnect again. A quick online search indicated that this was not an isolated issue.

I have 20+ devices on the WiFi in my home, including cameras, smart-speakers, printers, TV's and computers, I do not have any connectivity issues. I'm not going to persevere and try to work around software bugs, it should work reliably out of the box.

I have returned it.

  @johnafish 

Your original post referenced the Archer AX1800 (this product: https://www.tp-link.com/us/home-networking/wifi-router/archer-ax1800/), so my answer was about that router. Your newer message clarified, and you're describing the Archer TX20U Plus (https://www.tp-link.com/us/home-networking/usb-adapter/archer-tx20u-plus/). Thank you.

I totally agree a product should work out of the box (after it's fully installed). Since you already returned it, there's nothing we can do to solve the problem. This info below is just FYI. From your two descriptions/posts, it was possibly (1) a WiFi (signal or network) issue, or (2) an issue between Windows and the adapter/driver (not necessarily caused by the adapter/driver).

(1) You said you had to hit the "Connect" button in Windows, because the connection between Windows and the network/SSID dropped (it's a "chain of connections": Windows connects to the adapter's driver, that driver connects to the adapter hardware, and the adapter hardware connects to a specific network/SSID). Something in that chain "broke". Such breaks occur most often in the 3rd part, between the adapter and the network. That's due to a "signal or network" problem. Either there's interference in the signals (radio waves), or there's a problem with the network setup/connection (which don't affect low speed connections, but are seen mostly in high-speed connections as with a PC). Probably in your setup there isn't too much signal interference, since you have 20+ devices on your network (presumably all are working, though it's still possible they work with a degraded signal caused by interference, by constantly re-transmitting). This suggests the cause was a network connection problem (between Windows and your network's SSID/router). If your network has more than one SSID, then you may have told Windows to "Connect automatically" to any of those SSIDs. This would cause exactly what you're experiencing (causing Windows to disconnect from one network, and try to connect to another with a stronger signal). This can occur if your router is setup for dual-radio networks (2.4 GHz and 5 GHz) both sharing the same SSID. Since WiFi adapters are relatively simple devices, compared to routers, I would have looked next at your router and its settings. We don't know which (the adapter or router) was causing the disconnections.

(2) The other possible cause (though much less likely) could have been due to Windows' driver module & other drivers/configuration. In Windows, a disconnection from an SSID can be "initiated" (caused) by either Windows itself, by the hardware (adapter's) driver, or by the adapter's hardware. In your case, it's very unlikely the adapter hardware caused this (unless you had the adapter plugged into a USB hub with many ports, and it wasn't getting enough DC power). In Windows' Wi-Fi subsection, Windows never disconnects a driver on its own. If/when it disconnects (from a WiFi adapter), it's because "some" WiFi device told it to do so (this means either the currently connected WiFi adapter told it to disconnect or some other WiFi adapter/driver previously installed in your OS told it to disconnect). Maybe your PC has a built-in WiFi adapter, that could be "telling" Windows to disconnect all other adapters and to "let me connect" (in which case Windows will forcefully disconnect the TX20U+ adapter, and will give a chance to the built-in adapter). Note that if your PC's built-in WiFi adapter stopped working, it's likely its driver is still there (and can still interfere). Also, Windows remembers all previous WiFi adapters you used on that computer, and can switch to one of those (to their driver), under some situations. So the problem may have been caused by another older driver in your Windows installation.

The following sentence from your post helped greatly in understanding your problem: "This adapter constantly disconnected, it would reconnect if I selected "connect" in windows". Thank you for explaining. Without understanding the root problem, others can't help solve them. Computing/networking is a very (very!) complicated area, and it's not as simple as "plug and play" anymore (we all wish it was). Too many things can interfere, literally. From your descriptions, it doesn't sound like the adapter (or its firmware/driver) caused the problem you experienced. (Lastly, reading posts online by people experiencing problems isn't a good way to assess what's happening, or of a product's quality, since in each of those cases there are likely very different causes and even in some cases multiple causes). Rest assured, most networking/Wi-Fi problems can be solved, once the root problem is understood.

Anyway, good luck in getting your computer connected. I know it can be frustrating.