When Wordfence detects that your site is behind a “reverse proxy”, you may need to adjust the option How does Wordfence get IPs on the Dashboard > Global Options page in the “General Wordfence Options” section, or by clicking the link in the admin notice that warns you about the issue. This includes the following message, followed by a recommendation:
Your 'How does Wordfence get IPs' setting is misconfigured
Solution: You can click the link in the message to apply the recommended setting, or you can adjust the setting manually.
If you do not want this scan to run, this can be disabled on the options page at Scan for misconfigured How does Wordfence get IPs. Wordfence also runs this check upon activation, to ensure that your settings are correct.
For advanced users, there are two constants that can be set to control this feature. (See Wordfence constants for advanced configuration: WORDFENCE_DISABLE_MISCONFIGURED_HOWGETIPS and WORDFENCE_CHECKHOWGETIPS_TIMEOUT.)
If you have dismissed the admin notice about this option being misconfigured, it can reappear when a new version of Wordfence is installed, to be sure you are aware of the issue. If you do not want the admin notice to reappear, you can use the constant above to disable the notice permanently.