If you restart a network server, the company passwords are reset. make sure to give new ones, or someone else may log in and mess with your company.

Thanks. I did issue a new password.

Does OpenTTd rate limit password attacks ?

I don't think OpenTTD rate limits password entry, but I think it would be a good idea to start rate-limiting password entry. The rate limit should be able to be configured at least in openttd.cfg.

I tested further but now cannot figure out how my old trains get restarted, it does not seem to be from loading a save game into multiplayer mode.

Changed topic.

Should there be a new message when a client tries to join, but has exceeded the rate limit in doing so? For example, "You have attempted to join [the game] too many times. Please wait …"

Is there a point in doing so though? If they are typing passwords by hand, then they will never be fast enough to be a threat to anything. If they are using some automated script, they would be able to circumvent this by starting a new client (or writing the packets so that it looks like it's from a new client), and you'd have to resort to rate limits based on the client IP address.

We are in the process of replacing passwords with something more secure: #8420

This would resolve this ticket, I think.