I'm severely annoyed at the OpenWRT provided ACME* packages, especially the one using acme.sh
It simply ignores the request to use EC keys.
It ignores the webroot setting, but warns it's deprecated. It falls back to standalone then and screams and shouts that uhttpd is already running. Of course. I run LuCI.
Maybe I have more luck with uacme...

Managed to setup certificate renewal on my OpenWRT with some hacking.

root@OpenWrt-ER:/etc/uacme# cat uacme.sh
#!/bin/sh -x

## uacme wrapper
## set all the default arguments

uacme -a https://srv-acme.lan/acme/acme/directory -v -c /etc/uacme -t ec $@
root@OpenWrt-ER:/etc/uacme# cat owrt.sh
#!/bin/sh -x

# wrapper for uacme.sh, i.e. the issue/renewal hook
# needed because OWRT removed CHALLENGE_PATH from the upstream script?

export CHALLENGE_PATH="/www/.well-known/acme-challenge/"
/usr/share/uacme/uacme.sh $@

#openwrt #acme #uacme