Messing around with MAC filtering and sometimes my internets dont work

(Please don't turn this into a discussion about MAC filtering vs password protection ok)

Ok so I fiddled with my router settings so now only whitelisted MAC addresses can connect but ever since I started doing that every now and then my router is randomly unable to connect to the internet? And then it's fine again later. There doesn't seem to be any sort of pattern, power cycling everything does nothing, idk it just decides it's not working and then just as suddenly decides everything is ok.

Probably an unrelated problem with your carrier.

You know MAC addresses can be spoofed and-------

Can you still connect to the router when it's "down"?