ZTE F8648P Optical Network Router (ONR)

Check the light indicator on your device. 

ZTE F8648P Optical Network Router (ONR) no power light
ZTE F8648P Optical Network Router (ONR) Red power light
ZTE F8648P Optical Network Router (ONR) No PON/internet light
ZTE F8648P Optical Network Router (ONR) Red PON light
ZTE F8648P Optical Network Router (ONR) No LAN light