I feel your pain. IN the last month my wi fi will quit operating with no connectivity to devices. I find the modem to have all lights on and functional. Only solution was modem reboot after which wi fi would work fine for a day or so then problem will resurface. I got sick of the issue and reconnected my old Belkin router to the modem ethernet out jack and no furthur problems as I am running off my old router. My guess is the modem which is only a couple years old is faulty and router function is the problem. Not quite your issue but similar. I'm going to see if tech support can come out and troubleshoot as my online trouble shooting reveals nothing is a problem. I was fortunate I still had my Belkin router which still functions well.
As of yesterday my internet is not connecting. I have unplugged and plugged in the modem the wall socket everything. All the plugs are secure but it's still not working it is not connecting to the internet all the lights light up and blank except for the internet.
First, check here for any local outages;