@Kevin_Z This beta version worked perfectly. Thank you.

@banesi I find it temerarious to know it is a known bug - and a big security one. How could TP-Link didn't fix it already? It wouldd be nice to get a position from the company.

@Kevin_Z, Thanks for your reply. But it didn't work. I still get a wrong username/pw message. I'm convinced I'm not using the proper format for the username. Should I use \\TP-Share\username,...

I have an external HDD connected to my Archer C7 router through its USB port. I can only access it if I have "Enable Authentication" disabled. Then, I can access it through Win+R → \\TP-Share\....