The AX55 web interface is very limited when the router is operating as a satellite router in an EasyMesh network.  The only ways to reboot the satellite router are to:

1. Reboot using the GUI of the main router

2. Power down/power up the satellite router

3. Use the Tether app

Experience has shown that, with some range extenders, the main router's GUI reboot icon for the satellite device does not work when the wireless signals are weak.  Not tested yet, the same may be true for the satellite router.  There should be another way to reboot the router without having to physically access the router to power it down and back up again.  Also there are some of us who prefer to not use the Tether app.

Recommendation:  Add the same Reboot option (under System) that exists in the main router GUI to the satellite router GUI including the Reboot Schedule feature.