@y2ken 

Usually it is both off, then the modem on, and when completely up, the router.

The reason being the modem will 'remember' the last MAC address it saw. Something it can't connect by just switching devices attached to it. Powering off the modem cause it to 'see' the new device as it no longer has the old MAC address in memory.

However, if both were off when you connected the router to the modem, it may not matter if the router is on or off? Router should see the Internet signal when it appears, but this could take a minute or so for the modem to come up completely. About the same as when your ISP has a  problem and the Internet drops, and when it comes back on, the router sees that and connects to the Internet.

@IrvSp 

Thanks, I always thought that the Modem should be turned on first since it's 'first in line' from the wall connection but was concerned by the contradiction in the instructions.

I was having a problem with my previous 5 year old router not being able to detect the internet with my new Modem and didn't want to end up with THAT situation again!

I figured it was time to upgrade to a wifi 6 router anyway so I'm hoping that it'll go smoothly. Fingers crossed.