pfSense » pfSense Docs

https://docs.netgate.com/pfsense/en/latest/usermanager/radius.html#radius-configuration

Authentication Timeout
Controls how long, in seconds, that the RADIUS server may take to respond to an authentication request. If left blank, the default value is 5 seconds. If an interactive two-factor authentication system is in use, increase this timeout to account for how long it will take the user to receive and enter a token, which can be 60-120 seconds or more if it must wait for an external action such as a phone call, SMS message, etc.

There should be a note saying that there will be three attempts. So total timeout will be 3 x Authentication Timeout in a case when the server is unreachable.