Discourse uses the
max new accounts per registration ip Site Setting to limit the number of accounts that can be created from a single IP address which has no trust level 2 or higher users associated with that IP address.
There may be times when you expect many new users to sign up from a single IP address. To allow these users to sign up, you can either increase the
max new accounts per registration ip Site Setting for all users, or you can allow the IP address through the Screened IPs list.
The Screened IPs list is found at Admin/Logs/Screened IPs. To allow an IP address, enter it in the New field, select ‘Allow’ from the dropdown menu, and then click the Add button: