Suggestions of similar web pages in the event of a navigation error must be disabled.

This setting allows Microsoft Edge to issue a connection to a web service to generate URL and search suggestions for connectivity issues such as DNS errors. If this policy is enabled, a web service is used to generate URL and search suggestions for network errors. If this policy is disabled, no calls to the web service are made and a standard error page is shown. If this policy is not configured, Microsoft Edge respects the user preference that is set under Services at edge://settings/privacy. Specifically, there is a "Suggest similar pages when a webpage can't be found" toggle, which the user can switch on or off. Note that if this policy has been enabled (AlternateErrorPagesEnabled), the "Suggest similar pages when a webpage can't be found setting" is turned on, but the user cannot change the setting by using the toggle. If this policy is disabled, the "Suggest similar pages when a webpage can't be found" setting is turned off, and the user cannot change the setting by using the toggle.