I have a problem with Thunar on Ubuntu. I have a couple of sftp connections in the side panel. These connect fine on first use, but Thunar provides no way to disconnect them cleanly, and after a certain time without use, they disconnect.

If I try to use them again, after they have auto-disconnected, Thunar crashes. I can avoid this by using Gigolo to disconnect, however, I have no way to reconnect to them, without rebooting (which is a pain).

If I try to establish a new connection, I get this error: 'Failed to open "/ on remote-server". The name :1.330 was not provided by any .service files.'

Any one able to suggest a fix?

I've found a workaround: pkill -s SIGHUP Thunar

It would be nice to fix it properly however.

You can try setting these directives on the server's sshd_config file
ClientAliveInterval 60
ClientAliveCountMax 2

and/or on the client ssh_config or a ~/.ssh/config file
ServerAliveInterval 240
ServerAliveCountMax 2

Another workaround would be to install sshfs and use autofs or systemd automount instead of using thunar's builtin gvfs.