Here’s something that I had observed today.
When attempting to connect to my webhost today I found that it would accept my username and password however, when initiating TLS, it would timeout even though my website was up and I had seemingly reliable connectivity to my webhost. In order to resolve this problem I tried a couple of things.
Firstly, I cleared the certificate cache just in case I had a corrupted certificate store. FileZilla doesn’t expose the ability to remove individual certificates so you will need to go and manually delete the “trustedcerts.xml” file in the following location in Windows Vista or 7:
… or, for Windows XP:
C:\Documents and Settings\%username%\Application Data\FileZilla
Another thing that I had found is that my computer had strangely run low on system resources (strange for a 64-bit Windows installation with 12GB of RAM but maybe I just had way too many browser tabs open). In order to remedy this I closed all of my tabs and browsers to get things back to normal.
After all of that, I was able to connect to my webhost using TLS once again (after accepting the certificate upon successful connection).