In theory, this shouldn't matter; browsers can resume a download where they left off. What matters is that the signature or checksum of the downloaded ISO file matches exactly the one listed in the website.
Try using another USB, and another physical port for it. Otherwise, I'm tempted to suggest following this instructions, but I'm not sure if this is the issue. Also, check the file at /var/log/syslog to see if there are any errors (this should be when the error appears). You can use the built-in text editor (don't use LibreOffice) or through the terminal:
sudo less /var/log/syslog
and press G to scroll all the way down where the most recent logs will appear.