I prefer to assign an external name to an internal device and grab a free SSL cert from LetsEncrypt, but using DNS challenge instead as internal IP addresses aren't reachable by their servers.
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Yes, I sometimes think about that, but have come to the conclusion that it's not likely to make any difference. If someone is trying to infiltrate my home network, then it's not going to really help them to know internal IP addresses as by the time they get to use them, they're already in.