Gateway authentication failure message

I've tried to reset the modem

I've unplugged it -

I've held down the reset button - done all the things.

All the lights are blinking green - but I still cannot connect to the wifi - "Gateway authentication failure" every time

Tried connecting to 192.168.1.254 --- per some online digging for the answer / help but it will not connect

My wifi, my phone line, and my tv does not work.

i'm connected via a very unstable hotspot

No outages are reported in the area.

I was on hold with ATT for 56 minutes and the call was disconnected.

please help me