[stavros]

You can get a static prefix from your ISP. After you get the static prefix, it's up to your local network to make the local parts of the address static. There's no reason why your DHCP server can't give the device a static address, it's not like it's going to run out.

Then again, you don't need a static address to get a TLS certificate. You don't need an address at all! All you need is a domain name.

[mort96]

Some of the devices I'm talking about are running on my own residential internet connection or my sister's. Some are running on whatever corporate or residential or 4G network happens to exist where I need to interact with them. Some are running on whatever network the user has.

How does your proposed suggestion of getting a static prefix from an ISP apply to those situations? Should I start calling customers to get them to ask their ISP for a static IP address?

> Then again, you don't need a static address to get a TLS certificate. You don't need an address at all! All you need is a domain name.

I don't understand what you think this solves.