These buttons become active when the search results for connection history include devices that have connected multiple times within the specified period.
For example, if a device was connected to the network twice, first from 9:00 a.m. to 12:00 p.m. and then again from 4:00 p.m. to 6:00 p.m., and you search the connection history for that entire day, the search results will include both of those connection records. In that situation, when you click the icon of the device, the buttons become active. By clicking the buttons, you can switch between the multiple search results and display them in the "Device Connection Status" section.