In a suitation where the master or replica IP address has changed on the servers due to some bussiness requirements then you must update the new IP address(es) in the scenario.
In the left hand pane of the scenario manager expand the scenario and select the master or replica whose IP address have been changed recently.
Now on the right hand pane go to properties-> Host Connection->Management IP Address . Please see the picture below.
If the scenario is a 'High Availbility' (HA) scenario then you have to do the additional step of changing the IP in the “High Availability Properties' tab in the right hand pane. Keep in mind if DNS redirection is not turned on you do not have to change the IP in that field. Please see the picture below.
Once those fields are updated please hit the save button in the scenario so those changes are put into place.