Well, the first answer is: It’s not possible - without manually hassle - to use LE with DDNS.
The retrospective answer is: I’ve spent the last 3 hours writing a script that does exactly this job.
It even works - to my own surprise. BUT: It’s really a dirty, first version of a script that has the potential to kill the entire router. I would not recommend anyone to run it - unless you have backups. It does not support renewing LE certs now, but I’ll add this feature in a few weeks.
As I had no idea about OpenWrt before, I first had to familiarize myself with all the logic. I will therefore completely rewrite the script in the new year.
It’s a really early stage and definitely not ready for production use. It may break your router, your computer, your network or anything else. It may even burn down your house.
You have been warned!
Before usage:
- Enable DDNS. Make sure your DDNS IP resolves to your WAN IP.
- Disable VPN!