Apache Continually Resetting To Port 443

I’ve encountered an issue with my website that I can’t seem to find a solution for, after multiple days of searching. In order to run the website, ports 80 and 443 need to be free. Apache uses those ports as a default, so that creates a conflict that causes the website to not go up. I’ve gotten Apache to switch ports from 80 to 8081, but when I try the same thing with port 443 (switching to port 9090), it continually resets back to 443. It’s driving me up the wall!

I’m very much a beginner with Linux and website code as a whole, so please be patient with me- if it comes down to it, I can try to make the website itself listen to a different port, but that’s a process I don’t even know how to begin. Both ports should be open and functional- port 8081 is for certain.

I don’t know what logs would be relevant here, but I’d be happy to fetch whatever’s needed. Currently, it’s running on Debian 9. This whole issue started when ACME v1 was shut down and I updated to ACME v2- beforehand I barely had to touch the code on my site at all, as it was a fork of a now-abandoned project. Which does mean I don’t know it as well as I likely should… Whoops.

Thank you so much for taking the time to look at my question, and apologies in advance if I miss something obvious! Any advice at all is greatly appreciated