Mi box 4k

I'm feeling soo frustrated with the MI Box 4k.I just bought Mi box S , and it connected to WiFi and everything was working fine, but then after sometime, it showed the message not able to connect to WiFi, it doesn’t show my home modem router anymore in the WiFi connections, I tried to factory reset mi box but still it’s not able to show my WiFi router, it shows other connections in my vicinity, my neighbor WiFi even my personal mobile phone hotspot but it doesn’t show my home router. I have tried restarting, resetting and rebooting to factory settings with no success. I even left it unplugged overnight with no success