Hello @revv0 

Sorry for the late reply. 

Did you try the chipset driver for Archer T3U and see if it helps improve the performance 

https://community.tp-link.com/en/home/forum/topic/509006

May I know the model of router, and did you try to change 5Ghz channel to Band1 channels like 36/40/44/48?

When 'the T3U will crash and stop working'  I have a photo of error if any error pops up? Did you recently change any Wifi settings on router? 

Thank you

Hello @revv0 

For ' will hear the USB disconnect sound when I try to connect to 5 GHz,'  may I know is it a reproducible issue, do you mean every time when adapter to connect to 5Ghz, you will hear the USB disconnection sound? As the issue sounds unusual, I would like to create a support email and escalate your case. 

- If the driver in the disk/ CD worked fine, try to install the old driver back  

- If you hear the USB disconnection sound

1.try a different USB port, like a USB 3.0 / USB 2.0 
2. Update driver for USB port, here is a guide found online that might help with USB not recognize issue:
https://docs.microsoft.com/en-us/troubleshoot/windows-server/backup-and-storage/usb-device-not-recognized-error

Can you help confirm some details here to help locate the issue 

1) may I have a link of the driver you downloaded from tp-link website, does CD driver work fine right now

2) May I have a photo of the  computer motherboard information Windows version 

How to check driver version of TP-Link adapters and system information of your computer?

3) May I know the model of router? Thank you