Can't use port 443

I remixed the reverse-proxy project for my school and tried to add it to my custom domain. When I tried it with the domain, I received a 525 error from Cloudflare. I looked at the support page and it said change the port to 443. I tried and I know Glitch has that port open. And got an EACCES error in the logs stating that the port was closed

Can you lower your SSL level in cloudflare?

I have and it works as intended. But it shouldn’t do this. I wonder if it is something in the code doing this. (this is a direct remix) It is odd behavior.

So, update. I can use it, but I can’t acess any sites. I really want to use the custom domain instead of (By the way, I am using the proxy for my classmates because the school blocked really innocent pictures in the google search, such as dogs, and we need pictures for an assignment.)