Could a firewall be causing the 'connection timed out' error in FileZilla?

Yes, a firewall is a common culprit. Your computer's firewall or the server's firewall might be blocking FileZilla's connection attempts. You'll need to ensure that FileZilla (or the FTP port, typically 21 for standard FTP or 22 for SFTP) is allowed through both firewalls. Consult your firewall's documentation for instructions on adding exceptions.