I'm a beginner in networking things but due to my ISP I can only open a certain range of ports in my router to be accessible from the outside of my network (something like ports 11000-11500).
That means I can't open port 443 to access my reverse proxy from the outside. Is it possible to redirect all traffic that's coming from one of the ports in the range to port 443 of my server?
I haven't found that possibility in my router (Fritzbox 7530) so is there a way to do this on my server (running Fedora Server)?
The reasonable way to approach this problem would have been to ask a follow up question, rather than bitching at someone for not answer in the exact format you required. You're the beggar here, you get zero fucking say in how much or how little people choose to help you.
Based on the original post though I am 100% sure that OP has already seen this page, already tried it, and therefore knows that the warning under 2.10.b. applies to the OP's case (i.e. FritzBox doesn't allow it from UI because the ISP doesn't allow it - that honestly had me wondering just how the FritzBox knows the ISP doesn't allow it, but that's a different topic).
(Why point out the distinction? For future readers. I can imagine some braindead ISP somewhere (likely a super cheap reseller) offering DS Lite but then not knowing about PCP, and either not offering port forwarding at all - or they do but you have to fill out a form and snail mail them and then they snail mail you back a printed letter containing a list of port mappings.)