It's either server or network issue. There's not much we can help you with here, unless you can connect with any other client using the same protocol from the same local machine.

Hello,
I've been using WinSCP for years to update my website without issue. Today, suddenly, when I try to login, a laconic error message flashes out immediately: "Connection failed" (written twice). I don't know if it comes from my web host or the program, so I suppose I'll contact support from both sides.

Running on Windows 10, login parameters are pre-saved, so I never had to do anything else than click on "login" and then drag and drop files. That's about the extent of my knowledge with this thing. :]

Thank you in advance for your assistance.
Regards.