Seems like curl does not find ca-certificates. I tried to use dyndns and had no luck with it (curl error 77 in logs). Needed to install wget to get things working (along with ca-certificates).
Curl seems to insist on looking at /etc/ssl/ca-certificates.crt, despite it supposedly should support the argument --capath:
I'm still a bit dumbfounded, wether curl should work or not without this bundle. Previously, it used to, at least according to Wiki? Also the command line parameters hint it should work by giving a directory to it? But it doesn't.
However, things (whatever I need to do with the router) work for me fine, so I don't really care enough to dig into (curl documentation / whatever) any further. This is just a remark, maybe someone knows better (and can report a bug report upstream if needed).
I know that, I think we are talking different things here.
I had curl and ca-certificates installed as per Wiki (seems there are two nearly-identical pages which should be merged?). There clearly are certificates in /etc/ssl/certs, LUCI stops giving tips (as if SSL should be working), but it doesn't - neither from command line even if I try to point CURL in the right directory manually with --capath (and the dir clearly is populated by some certs).