Connection was reset

Hello,

I recently wished to create a minecraft server with my own PC when I’m not at home. I installed docker and put MineOS inside (with portainer running alongside).
I installed it a few days ago, and everytime I want to connect, my browser says (wich is Firefox btw) : " The connection was reset

The connection to the server was reset while the page was loading."

I checked a few things, wich didn’t fix anything :
-I am on localhost:8443 (myip:8443 gave the same result)
-No errors in the logs
-MineOS IS running on 0.0.0.0:8000->8000/tcp
-sudo lsof -i :8443 confirms it
-node and npm are installed (and are used)
-pinging my ip works (no timeout, now lost packets)
-My firewall is ‘inactive’ (ufw), but I don’t know why it would be on local

I am on Pop!_os 22.04 (based on ubuntu) and I am kind of new. Any kind of help would be appreciated.