I don't see any red notes. Not important.
I heartily agree with Rudy's latest comment.
Do you have a fixed IPv6 address? Can it be addressed from the public internet? Let's Encrypt server will prefer the IPv6 address if an AAAA record is in the DNS (update: for an http challenge).
Of course, any other clients will need to prefer IPv6 too if you want them to reach you that way. And, this assumes your ISP allows http inbound to your device.