I am baffled by this page.
It describes how to deal with a problem I'm having with SSL, but section 7 on the page makes a reference doing something with LuCI which doesn't look anything like the current LuCI menu/page structure (Using OpenWRT 18.06.1)
In LuCi, go to Services → uHTTPd
In the field for HTTPS Certificate, paste
In the field for HTTPS Private Key, paste
Hit save and apply.
The only place I can find anything about Services in LuCI is the System>Startup page, which will do various things to start and stop services, but has no sub-page apparent for any service, and no sign of the referenced fields.
I am guessing that there might be a way of doing this by editing /etc/init.d/uhttpd but I am a bit scared of breaking anything, (Yes, I know, back-up the file before editing, but we are dealing with logging in to the router... I am not an expert on Linux.)
Essentially, this needs checking to be sure it points to the right part of LuCI, and maybe re-phrasing. If there is a non-LuCI way of doing the job, that needs documenting too.