Problem trying to host a vaadin spring boot app on DO

I’m trying to host a vaadin springboot app using docker on a digital ocean droplet. The droplet has 1GB RAM and is capable of running the image.
When I run the application, all my ‘api’ endpoints appear and work, but my Vaadin UI doesn’t. When I try to connect to the UI it just keeps loading forever.

I am correctly mapping the docker port to the out port.
My docker works as tested in the local dev machine.

My docker file:

FROM openjdk:8-jdk-alpine
ADD ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

Also, I tried running the app without docker and I’m getting the same issue.
No pages respond with nothing and there are no errors in the server.

Just tested also in a brand new droplet with a brand new debian. It worked for a while and then it stopped working. Same behaviour. Api works fine and the UI doesn’t load.