Network question, nginx, cerbot, duckdns, Jellyfin

[mariobross2]

Hi, I’m not sure if I’m at the best place for that type of question, but let’s try it anyway.

Here is my setup:

DuckDNS address (something.duckdns.org) redirecting to my local IP and my router redirecting to my Raspberry Pi running Nginx redirecting to itself where I’m also hosting my Jellyfin server. On my Raspberry Pi, I’m using DietPi.

The question/problem:

From time to time, about 1 time every 6 months, I experience a weird situation where my Jellyfin server is not accessible from outside of my network. I don’t know much about the reasons, but the solution is to go to duckdns.org and manually change the IP to my local IP and change the Raspberry Pi “static gateway” to be my actual IP.

I’m quite confused with that because I thought my IP on duckdns.org would be updated automatically upon any change.

Also confused about the fact I need to change my “static gateway” to my IP. (For me, this is two different things)

Searching Google with that only gave me some very generic information about what “static gateway” is and nothing about why I need to set it as my IP. (If I set it to my router “static gateway”, it doesn’t work.)

I’m open to any suggestions from you guys.

Thank you very much and have a nice day.