Anytime you have major speed issues, 1) power modem, router, and PC off then back on. wait a bit and then test. 2) bypass the router by connecting your PC directly to the modem to see if it is your...

Check this out.. https://www.tp-link.com/us/faq-1538.html

Can you bypass the router and see if it is your ISP or modem?

1) True and false. For example WIFI 2.4 GHz on TP-Link AC1200 supports up to 300 Mpbs but 5 GHz supports up to 867 Mpbs per the specs. 2) False. Per specs, 600 and 1300 Mpbs. Bypass the router and...

The numbers seem to be reversed. Try a different speed test. Bypass the router and connect the computer direct to the modem and check your results to ensure it is the router.

Sounds like an issue with the drive since other drives work okay. The power draw may be to high for the router. May want to try a powered hub. Have you tried it on the 2.0 port of the router and have...