Because you're going to be hit by the next of the countless pre-authentication vulnerabilities that constantly pop up for appliance's like yours.
All your security measure will do absolutely nothing in that case.
I don't get why you don't just set up a VPN? It isn't more complicated than what you did, and offers far superior protection. And for 99% of use cases, you don't loose any functionality either.
Because you're going to be hit by the next of the countless pre-authentication vulnerabilities that constantly pop up for appliance's like yours.
All your security measure will do absolutely nothing in that case.
I don't get why you don't just set up a VPN? It isn't more complicated than what you did, and offers far superior protection. And for 99% of use cases, you don't loose any functionality either.