The first things to check:
- do you still have Internet access when using an wired (Ethernet) connection?
- does the connection return after you turn the modem and router off and on again one minute later?
- does it make a difference if you change channel or frequency band?
Just recently I am getting dropped from wi-fi on my laptop on CenturyLink modem. Is this a thing? It is happening hourly and sometimes it comes back, but I was without internet for 16 houras last night!