Switching SIM cards or switching to a secret 2nd number
Solution 1:
What would show up in my router logs if i was Switching sim cards or switching to a secret 2nd number .
Nothing.
One has nothing to do with the other.
Your router, routes IP traffic from your network another network; in this case the Internet.
Your SIM card is what enables you to access the carrier's cellular network. It's nothing more than an "access pass" to their network. It doesn't even have anything to do with your phone number, secret or not, because it's tied to your account.