Nextcloud in Docker next to IIS Website

Heya everyone,
I got the following setup:

Win10Pro PC as “Homeserver” with IIS activated and a Website running
Docker Desktop with nextcloud-aio containers installed

My Website was running without SSL, so I had no problem just using the device port 443 for the nextcloud via reverse proxy, however since I decided to install a Lets Encrypt Certificate in my IIS the Website now DOES use SSL and Port 443, and I can no longer access the Nextcloud, getting the error “502 - Web server received an invalid response while acting as a gateway or proxy server.”

I have already tried changing the Apache-Port (Which was 443 previously) to 11000 and also changing the Reverse Proxy Rule to instead go to that port

I’d love to keep the current setup, using IIS, and not switching to something else entirely, since it’s already all set up and working, so any advice thats not “how about you use X instead” would be great!

I’m willing to do a full reinstall of the Nextcloud however, since there’s no data inside yet

Thanks in advance!

I know you dont want to hear this but I’d recommend caddy server. It is simply amazing!

If you can explain to me in what way this would reliably solve my problem, I am willing to try