Http https transition in running system

Hello,
I made an installation as follows.

raspberry pi 4 4gb
open media vault 5.5.15-1 (procedural)
nextcloud 20, port 88, http
php 7.2.9
database mysql 10.3.25
internal ip address 192.168.0.21
external ip address xxx.xxx.xxx.xxx
My domain name is xxxxx.com
I redirected my domain name to the external ip through the provider.
I redirected the ports over the modem.

domain name: 88 / nextcloud works on web and mobile.
domain name: 90 open media vaults are running.
I can use it on the internet outside of home.

I want to switch from http to https, but none of the narrations fit my current structure.

I would like to ask you for help on the subject.

How can I switch from http to https without breaking the working system.

omv-docker-ngix-snap-lets encrpyt, etc. I’m so confused. Virtualhost: I could not fit what is written in the 80 files into my own structure: (

Thank you for your help.

Solved. I re-installed. I have ssl enabled.