I had a working DDNS configuration that seems to have broken when I upgraded to 20.02.0. Specifically, DDNS via SSL using nsupdate.info no longer works. ca-certificates was and is installed; libustream-openssl used to be installed but now isn't, since it conflicts with libustream-wolfssl, installed by default in 20.02.0. Here's the relevant section of /etc/config/ddns:
If the simplest fix involves ripping apart my OpenWrt installation and possibly recompiling packages, I think I'll just use another DDNS provider until this issue gets sorted out - I always keep two separate providers available anyway, for just this sort of eventuality.