Development Discussion Board

If you think you found something which is on the phpBB.com site, search for it on Google and use the link "In cache" to view a cached version of that webpage.

ACP -> Users and groups -> Ban e-mails/Ban IPs

At that time you reached a limit your host set of the amount of connections to the database that may be made. If you get this error often, it would be a good idea to contact them and ask to increase the limit.

Maybe these articles will help you a bit.

Knowledge Base - phpBB3 Cross-site Sessions Integration
Knowledge Base - phpBB3 Sessions Integration

You can try to do an offline conversion, when you keep getting time-outs on your live board.
Knowledge Base - Offline Conversions

ACP -> General -> User registration settings -> "Enable COPPA"

Everyone with the admin permission "Can manage users" will recieve it. Not only people within the Administrators group.

Is there a way to set it so that warnings have no maximum duration? The default is set to 90 days before the warning expires. I would like it to be set so that it never expires, making a record of how many times we have had to warn a user.
Then just set it to something very high, like 9999 days ...

When you give an user that permission he is also able to see the browser agent of users in the "who is online" list and he can edit the settings, which users have set in their profile. (ACP -> Users and groups -> Manage users)