Can't do http, only https works Squid reverse proxy

[riukotashi]

Hello,
We are a group of students who are working on a infrastructure with pfsense.
As we are a group of students, many people who worked on the pfsense are not here anymore, so I'm not totally sure of what have been done. And the documentation of what have been done isn't existent.
Here is my problem :
We have a squid reverse proxy that works but I don't know why, we can't do http only https works.
It can be a problem because in case of we want to redirect http to https on the webserver (like apache) it is impossible.
An other case is that we can't use certbot to create certificates because it needs to use http to generate it, so that's doesn't work.

If you have any idea that can explain why http can't work or any solution to make it works tell me.

Thank you in advance