Yesterday I setup remote access to my QNAP NAS and wrote a guide for it, that I can reference later. Might be helpful for someone. This was my first time doing something like this. So any notes on my approach are also welcome.
Hopefully your DHCP server never goes down.
DHCP is a curial part of every network. When it goes down then you need to respond. Leases usually are given out for several days. Even then, to fix yoy DHCP you can just use a static address temporarily.
Similar stupid statements are: Hopefully your Switch never goes down. Hopefully your Router never goes down. Hopefully your Server never goes down. Hopefully your House never burns down.