MyBB sites, such as forum.vyos.net, enforce bad password policies:
Please correct the following errors before continuing: The password you entered is of invalid length. Please enter a password between 6 and 30 characters.
The 30-character limit doesn’t matter, it gets salted and hashed either way. It’s an entirely arbitrary limit that renders passwords less secure. Don’t do it.
Even better, call then passphrases, because that’s what they should be.